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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: BackCountry on March 26, 2014, 01:18:16 pm
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I just got this truck and it runs decent, but the valves are rattling very bad when accelerating or going up a decent incline. I've tried setting the timing with a light but if i get the mark anywhere near the mark gauge it dies. I can't even get it close to the plate.
the previous user plugged all the vacuum lines except the ones going to the distributor and brakes and climate controls on dash. It also runs rough at high speeds(like interstate speeds). new plugs, cap, rotor also
any idea?
also, previous owner removed drivers side fuel tank and also the switching valve. the fuel gauge always reads 1/2 tank. in the wire harness that should be plugged into the switching valve I've jumpered the pink/black to the pink but still no action on gauge. not sure if I'm doing it right or if there's something else I need to do. tank selector switch is new and set to LH tank also
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Welcome to the site first off. We need more info on your engine to help you like what it is.
As far as the fuel switching issue, the manuals are in the tech section here (http://forum.73-87chevytrucks.com/smforum/index.php?topic=25639.msg234397#new), along with the wiring manuals. It sounds like you might have to start tracing power sources or lack thereof.
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welcome to the site as well. I agree with bake start tracing power sources and check the grounds too.
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Sorry, my engine is the 305 with an edelbrock 1405 carb. new cooling system, new plugs, cap and rotor.
And I have the wiring diagram, and I have power on the pink wire, though not sure I'm supposed to. Wiring is absolutely not my thing :)
This is the wiring diagram I found that led me to think if I attached th pink/black to the pink I'd have it working.
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also, previous owner removed drivers side fuel tank and also the switching valve. the fuel gauge always reads 1/2 tank. in the wire harness that should be plugged into the switching valve I've jumpered the pink/black to the pink but still no action on gauge. not sure if I'm doing it right or if there's something else I need to do. tank selector switch is new and set to LH tank also
OK we can work through this, and I am sure others will help with this. I want to make sure we are on the same page and as others read this they will know where this stands.
You said above that you jumper-ed the pink/black wire to the pink wire on the fuel tank selector valve and meter switch correct ? If so you just connected the left tank to the right tank, which as I understand the right tank does not exist.
If you look at the fuel tank selector valve & meter switch box in your wiring diagram you posted. Inside the box you will see the diagram for the actual switching mechanisms for the left and right fuel tanks. (it says left on the very top wire)
So your left fuel tank is wire .8 PNK/WHT-930, (your nonexistent right tank should have been .8 PNK/BLK-830, which at the bottom of the box you can see the right switch mechanism inside the switching valve, you will notice that it is open in this pic).
This might get a little confusing but I am trying to keep everything in order so you can understand.
Wires .8 DK GRN-54 and .8 LT GRN-53 are the wires that go from the fuel tank selector valve & meter switch to the fuel tank selector switch inside the cab on the dash, while wire .8 PNK-30 is the actual wire that goes to the cluster to send the fuel gauge the signal (so it can show you where your gas level should be).
Here is where I am not going to confuse you with wiring 101. If you want the simplest solution to your problem, you can bypass the fuel tank selector valve & meter switch mechanism and the fuel tank selector switch inside your cab by hooking wires .8 PNK/WHT-930 to wire .8 PNK-30 down by the fuel tank selector valve & meter switch . This will put the signal from the left tank straight to the cluster so the gauge can read it.
If you want to ever re-install the second tank you will need this wiring diagram. (Or if you want to know how the rest of this diagram works I could do a write up and post it, but it might be a little long winded). ;D ;D
I want to thank you for posting this wiring diagram with your problem, I have searched for a dual tank wiring diagram in our manuals in the tech section but have not found one yet. I will be book marking this post for that wiring diagram, again thank you.
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thank you so much for the detailed post. the passenger side fuel tank is what is still there and it seems to be the one with the pink/black wire coming from it
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still working on the fuel gauge issue, might need a new sender, but was still hoping someone could give me advice on the valve rattle.
wife will have to drive this next week and wanna get this fixed before she needs it.
Thanks in advance
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Have you checked valve lash? Take off the valve covers and see if you can move the rockers by hand easily
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Have you checked valve lash? Take off the valve covers and see if you can move the rockers by hand easily
I thought I already posted this, sorry, this is what I would do first and the easiest solution if it works.
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...the valves are rattling very bad when accelerating or going up a decent incline. I've tried setting the timing with a light but if i get the mark anywhere near the mark gauge it dies. I can't even get it close to the plate....
Are the valves clattering or is it pinging excessively under load? Check the harmonic balancer for a slipped outer ring and check the timing chain for excessive wear. The ignition timing is probably way off.
If the valves are clattering, verify oil pressure with a mechanical gauge. How does the oil look? Let one drip of oil from the dip stick drop on the pad of your finger. Does it hold together in a tight little puddle or does it spread out and track along your finger print?
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Thanks for the replies, unfortuneatly I don't have internet at home yet(moving atm, prob later this week) so didn't see these until today, so I'll check this tonight.
Thanks so much again for all the suggestions, I'll keep you posted
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Have you checked valve lash? Take off the valve covers and see if you can move the rockers by hand easily
I got the valve covers off, but not too much experience in this area. The rockers move side to side, but not really up and down by hand.
and BD, it sounds to me like valves rattling, but the timing is off. but I've been setting it by ear, cause with the light, if I get my marks anywhere near each other the truck dies. Also, oil looks good, sticks together(but could use a change, next weekend) and according to gauge on dash(not dummy light) pressure is good
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Does it look like the timing chain cover has been replaced? My 83 has the timing tab at the top straight up and down with the engine (12 o'clockif you were looking straight on) but many of the aftermarket ones the timing tab is offset to the drivers side (about 2 o'clock if you were looking straight on) therefore if someone replaced the cover and not the balancer, your timing tab would be off by about 2.5 inches
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I don't think I remember seeing that but I'll check again when i get home to be sure and update this post.
- Yeah, doesn't look like the timing chain cover's been off as best I can tell.
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read in my manual that I could check my timing by setting my marks on pulley and plate and making sure rotor was pointing to #1 plug on distro cap. and mine points to #6. Do I just need to do another full rotation? Does it point to #6 on the exhaust stroke?
Probably simple question but didn't have time to do it last night before the storms
ty again
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The timing marks line up every engine revolution, but the engine rotates "twice" for each complete revolution of the distributor. For the distributor rotor to point toward #1 you needed to rotate the engine one more revolution.
Unless you are timing off of the wrong cylinder, the problem you describe trying to set the timing with your light suggests a spun or wrong balancer. The method you described from your manual is too crude to determine whether the balancer has slipped and that the timing marks are accurate. For this purpose, use a piston stop. See the thread: Not 100% what's wrong here (http://forum.73-87chevytrucks.com/smforum/index.php?topic=26872.msg223842#msg223842) for an explanation. You should also check the amount of play in the timing chain - see, Re: 86 C10 Loping (http://forum.73-87chevytrucks.com/smforum/index.php?topic=27593.msg229607#msg229607) for the procedure. Verifying the timing marks and chain play are not difficult, and both are fundamental to a properly running engine.
On the 'valve rattle,' what does the oil pressure gauge indicate and what oil are you using?
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ok, update, I ran seafoam for about a week and did an oilchange to fix the valve rattle.
yesterday I put a new fuel sending unit in the tank to get my fuel gauge working. that gives me my next problem: the needle on the gauge sees to be about 1/4 turn off.
as in: when the tank is full the needle us just below the E on the gauge. when the tank is empty the needle is down by the word Unleaded at the bottom of the gauge window.
it's like the gauge is moving up and down instead of side to side - like I need to turn the whole gauge clockwise a 1/4 of a turn. is this possible or is there another fix?
BTW: I gave this issue its own thread in "Electrical" directory