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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: plowman on January 12, 2017, 12:33:22 pm
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Hello
I'm having some trouble trying to get my truck started and I'm hoping someone here can help me.
The truck is an 87' GMC V1500, it came with a 305 and a 700R4 from the factory. The 305 had a catostrophic failure and needed to be replaced. It was running fine until it had a bearing issue and started knocking.
So I picked up a GM crate 350, new injectors, knock sensor, and ESC module.
At first I had issues getting to to fire and determined it was 180 degrees out of alignment. That was fixed and the backfiring stopped. At this point it would start to fire, but It would not catch and run. I insured cylinder one was a tdc and have checked the wires multiple times. I have tried to adjust the timing a little and it sounds like it wants to start but just won't.
Since then I have replaced the fuel pump , pump relay, and fuel filter (although I can see fuel coming out of the injectors, and hear the pump priming when I turn the ignition on). I have also ordered a pressure gauge and fitting for the filter to confirm actual fuel pressure.
I have also replaced the entire distributor with a new AC Delco oem replacement. The old one was rather rusted and the contact didn't seem great. I was concerned the pickup or sensor was bad and not sending the injector pulses.
This didn't seem to have any effect so I ordered myself a code reader to see if I could pull any helpful info off the computer to help get me on the right track. Unfortunately it spit out 10 codes at me and did nothing to help me narrow down my issue.
The code reader gave the the following codes.
42
35
33
32
31
55
54
52
51
43
After seeing these the ECM seemed to be a fairly common thing amongst the codes. I double checked my grounds and decided to order a replacement AC delco oem ECM. After putting the prom and memcal in the new ECM I checked the grounding and wiring one last time before hooking the battery back up.
The truck is a plow truck and the previous owner did the install and hacked the wiring up a little. Befor hooking the battery back up
I noticed I had been hooking a grounding cable directly to the positive terminal (the truck has a standard neg cable terminal and multiple additional
Wires on a threaded negative terminal, with only three wires on the threaded terminal on the positive side and no standard battery cable terminal). It has a brand new marine/rv battery.
I corrected the incorrect ground cable routing prior to trying to start on the new ECM. The truck did the same thing and seemed to throw out the same exact ten error codes afterwards.
There are multiple other supporting features nf items that were cleaned and or replaced but nothing that I can think of that would cause this. Has a new radiator and water pump, torque converter, an edelbrock manifold, I cleaned the tbi unit and rebuilt the fpr. I have a new set of headers but have reinstalled the factory manifolds and am trying to start it open header with the factory 02 sensor installed. All of the factory smog equipment was retained.
I don't know what I am missing.
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welcome from maryland. lets stop throwing parts at it (dont know whats left) but start trouble shooting. i wouldnt pay any attention to the check engine light as youve had a few problems and the engine isnt running right now.
so the engine will start and then just quit as soon as you let go of the key? or will it just shudder?
have you see if you can get it running on starting fluid?
what happens when you apply 12v to the red wire coming off the fuel pump relay?
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also
http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf
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It will only pop every other time or so when I hold the key down. With starting fluid it will pop every time but won't stay running. It won't stay running when I hold the key it just pops once then kinda sounds like it just stalls.
I'm. It sure how to go about applying 12 volts to that wire. I have a multimeter. It am not well versed in using it or even sure if that is the right tool for this job.
I tend to struggle with electrical which is what I feel like the underlying issue is here.
But any help is greatly appreciated. Thanks
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also
http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf
I already had this link open. It's one of the motivators for ordering the fuel pressure gauge.
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i know theres a picture of it somewhere. but if you look at the fuel pump relay it will be a red wire thats about 4" long with a spade connector on it. it may be buried in the wire loom but its the only wire thats about 4" (maybe 3) thats sticking out of the base of the relay
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I know the connector you are referencing.
Just not sure how to go about feeding 12v to it. I'm good with the mechanics nuts/bolts but Electrical is not my strong suit.
I'm invisioning a 12v battery with a wire or just finding a wire to run directly off the car battery. I'm not exactly sure where to source the 12v or how to feed it to the connector.
What am I looking for after I apply the 12v? Should the injectors just start spraying or am I just wanting to hear the pump turn on? When I hit the key they seem to dribble more than spray until it fires then it stops, seems to actually spray real quickly and dies off immediately.
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oh my bad. yes take a wire from your battery B+ and run it to that jumper wire. it will bypass the fuel pump relay and your pump will be on until you disconnect that wire.
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honestly i dont think it will help your issue. but i want to make sure the pump isnt turning off at some point. also check for spark during the cranking with more than one cylinder, and check your compression with a compression tester
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you can rent the compression and fuel testers at most parts store and a injector diode tester or the likes of one.
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I bought a fuel pressure tester that says it can do compression testing, so hopefully I can give those both a good testing when that shows up. I also got the fuel filter adapter to use as a source for the fuel pressure reading
In the mean time I will get power to that connector and insure my pump is staying on, and I'm thinking about trying to physically confirm the timing mark on the balancer is actually tdc for cyl 1.
An injector diode is the same as a noid light?
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yes
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Sounds like you have the distributor in wrong. How are you identifying #1 at TDCC?
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^^^^^ This.
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That was my first thought also.
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I have verified I have spark at the coil and at the #1 plug wire.
I had the distributor off 180 deg at first but have adjusted it since. I have a mark on the manifold where the #1 post originally pointed towards. I have the distributor inserted so that when fully seated in the oil pump my number one post is on the mark and the rotor is pointing at my #1 post.
I have been using the notch on the balancer to align #1 at tdc befor dropping the dizzy in.
So although I haven't popped the valve covers off, or been using the finger over spark plug method (which seems like it could be inprecise). I think the timing should be close enough to start.
I have spun it at least half way each way between the next posts, and even took all the wires off and pushed them over a spot so I could spin it further forward because the plugs were starting to hit the firewall.
I feel like it is electrical since it will fire but not stay running. But obviously I don't know what is wrong so all I put is welcome
The next thing on my list to check currently is fuel pressure but I am waiting on the fuel filter adapter. So maybe double checking the timing mark on the balancer and insuring cyl 1 is infact tdc should be on the list.
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tell you the truth i was stalling till these guys showed up but figured we could knock out some trouble shooting till they did.
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Did you replace the balancer? Rotate the crankshaft until you know #1 piston is all the way up. Using a mirror and a flash light you can physically see the piston all the way up. Mark the balancer with zero on the timing tab at that point.
Also you can buy a borescope for your phone for dirt cheap on ebay. Those work great too to peak inside the cylinder but for immediate results use the light if you don't have one
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The crate engine came from GM with a new balancer, I just installed the crank pulley
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The finger on #1 cylinder plug hole is not an unprecise way of ensuring you are on compression stroke. It is the best way to do it without pulling off the valve covers. I've done it for many years that way.
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There are two different indexing marks used on SBC balancers and often they are mismatched so you need to physically verify the mark at zero is truly TDC. Finger over the hole helps find the compression stroke but not necessarily TDC. Bottom line, do not trust the mark until you've verified it.
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If it fires off with the starter fluid and promptly dies sounds like a fuel starvation/delivery problem
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On my list of things to do today is to replace the injectors with a more reliable flow tested 350 set instead of the autozone slightly larger cop car injectors.
I will also be double checking the timing and resetting it to zero. this time unplugging a brown/grey wire near the brake booster that runs out of the main loom to a connector and back in. I have been told this should be disconnected to adjust timing. Done in this sequence unplug befor turning on, turn ignition on while adjusting the timing, turn off and reconnect.
I have not done this at all so I am a little hopeful here.
I will also pop the #1 spark plug out and confirm compression stroke and if I can make any determination on the balancer marking accuracy with a flashlight and no borescope. I'm gonna look at the cell phone borescopes today as well.
I think that's all I have to look at at this point though.
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New
So a little update.
After checking fuel pressure it was showing that as I turned the ignition on and cranked the fuel pressure would climb then immediately fall off.
I have double checked the lines and replaced the pump again.
When I jump the pump from the relay I can hear a missing sound coming from the tb. I can't tell if it is air coming in or leaking out but there doesn't seem to be fuel leaking anywhere..
It sounds like I can hear fuel running back in to the tank which I assume is the return line doings it's job.
I am assuming at this point that there are one of two things happening.
1. I did something wrong when rebuilding the pressure regulator, and installing the new diaphragm. now somehow it is not regulating pressure correctly and is not giving my injectors the proper pressure.
2. I am slightly skeptical that the hardline on the sender unit in the tank is cracking inside the tank where it meets the cap and the fuel pressure is leaking there and draining back in to the tank.
What do you guys think? Any recommendations on the next step?
A moment ago EditDeleteReport+ QuoteReply
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I agree with Vile. You need to get #1 at TDC on the compression stroke. I think you're off a tooth or 2 on the distributor. I wouldn't do anything else until you verify the timing marks line up with TDC and the distributor is correctly installed.
Yes, that wire has to be unplugged while setting the timing. It will set a code IIRC. You can't really set the timing until the engine is running.
From what I've seen Vile is an awesome mechanic. I would do whatever he suggests. If you do, it will be running shortly.
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I had a friend help me check the timing. He said it was off a tooth so we reset it, tried again, and rechecked. He had his finger on the plug so we could confirm compression stroke and then he watched the balancer while a cranked it over by hand. No change to speak of.
I am 95% sure it is fuel pressure at this point. I suspect the fuel pressure regulator. The filter adapter I used showed the system spike at first but was unable to hold fuel pressure.
I replaced the spring and diamphram in the regulator and I thought I had it in there ok. I can't see any wrinkles in the diamphram along the outer seal, but maybe the spring isn't seated correctly or something?
I really can't understand the hissing sound from the tb when I jump the fuel pump. I would think A leak in the system would cause fuel to be pushed out somewhere. Not what sounds to be an air or vacume leak?
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I think you missed the whole verify your TDC mark post or you are just ignoring it. Until you have verified that you are going to be spinning your wheels.
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I agree with Vile Zamboni. You have to have 3 things to make this motor run, Compression which it sounds like you have, Fuel which is a question and Spark at the correct time. Like in the previous post verify your timing is correct. The thing that concerns me is the noise you are hearing when running the fuel pump all the time. It should maintain fuel pressure until the battery goes dead. If it's not then something is incorrect in the fuel pressure regulator you rebuilt. A good rule of thumb is to always start with what has been worked on and make sure it is correct before throwing parts at it.
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I think you missed the whole verify your TDC mark post or you are just ignoring it. Until you have verified that you are going to be spinning your wheels.
In the post befor I mention very first thing we checked the timing. We pulled the plug and insured it was on compression stroke. From there I cranked it over by hand just enough to get the balancer mark to line up. We then rechecked the dirtibutor, found it off a tooth. Pulled the dizzy and got it set correctly.
We then tried to start it with no luck. Pulled the number one plug again to insure compression stroke with the finger and lined the balancer back up. Pulled the dist cap and insured we were still where we wanted to be.
Am I missing something? Is there something else you think I need to do to insure tdc? You want to borescopr it or something to insure the keyed balancers marking is in the correct place?
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Maybe this has been mentioned, but for around 10 bucks, you can get a piston stop tool. Why guess when it can be perfect. Simple to use, several learning videos to get you going.
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I think you missed the whole verify your TDC mark post or you are just ignoring it. Until you have verified that you are going to be spinning your wheels.
In the post before I mention very first thing we checked the timing. We pulled the plug and insured it was on compression stroke. From there I cranked it over by hand just enough to get the balancer mark to line up. We then rechecked the distributor, found it off a tooth. Pulled the dizzy and got it set correctly.
We then tried to start it with no luck. Pulled the number one plug again to insure compression stroke with the finger and lined the balancer back up. Pulled the dist cap and insured we were still where we wanted to be.
Am I missing something? Is there something else you think I need to do to insure tdc? You want to borescope it or something to insure the keyed balancers marking is in the correct place?
Realize that we base recommendations on what you tell us. Any assumption(s) that you make in your narrative is missing information. A few situations will result in the balancer timing marks being off (e.g., slipped balancer ring, replacement balancer with timing mark positioned for different year application, incorrect timing tab for an otherwise correct year balancer, excessively worn or slipped timing chain). For example:
(http://forum.73-87chevytrucks.com/smforum/index.php?action=dlattach;topic=34285.0;attach=34542;image) The image illustrates two timing tabs that are used for different year applications. The balancer can be correctly clocked only for one tab or the other, not both. Using the wrong timing tab for the balancer will throw the timing off by roughly one distributor tooth. On the other hand, if the timing chain has slipped, the balancer mark will be retarded at TDCC. If you rely on the timing marks with a slipped chain, ignition timing will similarly be retarded. You get the idea?
According to your description, you verified the timing marks based on assumptions that the balancer and timing tab were in perfect condition and properly matched by year. Rotate the engine to verified TDCC based on piston position and then compare the position of the timing marks to verify that they align. Without such verification the timing marks cannot be relied upon to be accurate and your diagnosis is based on false assumptions that can bite.
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Ok I understand. Just seems highly unlikely that a brand new crate motor from GM would have an incorrect balancer, or timing mark tab, and no reason or evidence to suspect of a worn or slipping chain. Just to reiterate this was a brand new GM crate engine from balancer to valve covers and I have not removed, modified, or replaced any of the factory installed parts.
But in order to rule out one more thing I will Get a piston stop to physically confirm tdc.
That being said I am fairly sure the hissing sound coming from the tb while I halve the fuel pump jumped and running seems like a more likely cause, and possibly a more promising place to spend my time.
I appreciate the help as I am truly stuck here. I apologize if I come off as dismissive, I have a few threads going on different forums and I am trying to keep up and absorb everything, and work through suggestions one at a time to cross off possibilities. I also really like asking question and being perfectly clear on things befor I move forward. I am pretty much physically working by myself, and i live in the boonies so it takes me some time to get new tools/parts when needed.
I blame any communication issues on the internet and the lack of a face to face dialog. Haha
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A piston stop is not designed to stop the piston at TDC rather it is used as a baseline for calibrating mechanical timing when installing a cam or timing set. Don't waste your money, instead get yourself a flexi-straw or piece of mechanics wire and stick it in the spark plug hole pointed at the piston. Slowly rotate the crankshaft until the piston is all the way up and mark the balancer at the zero mark.
For the record, it is not highly unlikely that they are mismatched, it's quite common actually especially with Mexican blocks. I've lost count of how many I've encountered that do not align. Once you've verified TDC at zero you can properly install the distributor. This whole quality check shouldn't take you very long, so start there before you start firing the parts cannon and wasting your money.
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If you continue to have trouble AFTER you verify the timing marks....
A hiss coming from the regulator, in itself, doesn't indicate a problem, necessarily. The TBI regulator returns fuel to the tank in order to manage constant pressure, so there is always a return flow when the pump is running. Your best approach to determine a faulty pressure regulator (or pump, or filter) is to measure fuel pressure using an accurate gauge. If fuel delivery to the throttle body is an issue, a pressure test will make it obvious.
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I'll look through the drawer and see if I can't find a flexible straw that may be able to do the job. How much travel does the piston have, or how long of a straw do I need to insure I don't drop it inside the engine?
i really didn't feel like pulling rockers of to use the piston stop so I like the idea of sticking something else in there, was just having a hard time thinking of something appropriate for the job.
I pulled the fuel filter and installed a fitting to check fuel pressure as there isn't really any other accessible places in the fuel system. I used a friends known good gauge as the fitting on my brand new gauge was different than the adapter. It showed the pressure spike up to the 15-20lb range upon firing up the ignition then immediately fell off and was unable to maintain pressure.
So again I think that the last comment was right and it seems obvious to me to be a fuel delivery issue. As I was changing the pump last time I confirmed the pump was sending fuel out of the tank, I cracked the line after the filter and confirmed I had fuel pumping past the filter. I haven't cracked the line at the tb as I don't want fuel all over the motor but I am fairly confident the lines between filter and tb aren't blocked.
It sounds as though I have fuel running back in to the tank from the return.
So if I have fuel at the regulator could a bad regulator diamphram cause low pressure through the system while returning fuel to the tank?
After physically confirming tdc, I'm leaning towards tearing the tb apart again and taking the regulator apart and checking the spring and diamphram install I have done.
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Typically, TBI fuel pressure runs at ~11 PSI, although 9-15 PSI is acceptable. The fuel pump should cycle on for ~2 seconds before shutting off, if you do not crank or start the engine. This is normal and expected. However, 15-20 PSI is not normal. Either the fuel gauge that you used is inaccurate (likely) or there is a problem with the FPR causing high pressure. Since high pressure would not starve the injectors for fuel, focus your attention on the diagnostic steps outlined by Vile. Don't underestimate his experience.