Author Topic: 305 Not Running Correctly. Unable to find problem.  (Read 912 times)

Offline StarrLion

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305 Not Running Correctly. Unable to find problem.
« on: September 14, 2021, 09:31:05 PM »
Hello everyone.  I am new here.  But I did search on here before I was approved to try and solve my problem.

85 3/4 ton utility bed 700R4 2 w/d Chevy. 

I have a 85 305 engine that started missing out under load.  And at certain cruising speeds.  I am at a lose to figure out why.  What I thought was going to be a simple fix has turned into any but.  I have owned the truck for 21 years now.  I have never had any problems with the engine till now.  Unknown miles.  And known history before I bought.  But it was still in stock configuration when I got it.

When the truck hits second gear it will act like it is cold.  Not warmed up yet.  Carburetor on this one.  It acts like fuel starvation.  You get up to speed and back off the throttle and then give it just a we bit to stay there.  It will spit and spatter and backfire sometimes.  Throttle down more it is fine.  It also does not do it all the time. 

What I have done.  Which has not solved this problem at all.

New fuel filter.  Then carb rebuild.  Then another carb.
New cap, rotor and modular Twice!  To make sure.  Dist. is 6 years old.  HEI Vac Advance. 
New plugs and wires.
New fuel pump.  Which the old one tested fine.  Flushed lines out also.
I can not find any vacuum leaks.  At idle it is 16.5 to 17.  Higher RPM 19 to 20.  Needle steady.
Does it with or with out vacuum advance hooked up.  Though not as bad with it not hooked up.
I could find nothing lose or wrong with the Distributor.  Tested advance at idle with a vacuum and it worked as should.
Plugs were correct color when removed.  Good shape really. 
Checking timing.  Checked advance with light.  All was fine.  I was more interested in seeing a unstable pattern then what it was set at.  I do not remember the number. But it was not way off or way advanced which could cause this also.

I have owned it for 21 years.  I have never put a timing chain on it.  That is my next thing to check.  If the timing chain is at the point it is causing retard timing in the engine.  I have noticed that since this has started.  There is no spark knock anymore.  This engine has always be really bad with knock.  Even with 93 Gas and the stat at 180 deg.  Not hearing the knock anymore has me at that, or this distributor is going bad.

Any idea or what I should test next would be grateful

Here is a photo of the timing chain.  I thought it would be out more then it is.  Rotating it CCW it lines up with the dot on both gears before moving the cam.  Rotating it CW it is at this photo before moving the cam.  I really thought the chain would be more out of alignment for as old it is, and how many miles it has on it.
   
« Last Edit: September 17, 2021, 12:22:03 PM by StarrLion »

Offline bedwards

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #1 on: September 17, 2021, 06:38:10 PM »
Man, that chain and sprocket set look gritty. Anyhow, I would try to wire around the ESC and see if that is your problem.
There are several threads on how to do it.
Also the aftermarket ignition modules are not as good as the original factory. Ask me how I know  =[

Offline StarrLion

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #2 on: September 17, 2021, 08:57:17 PM »
Thank You for your reply.

Yes.  I was disappointed in seeing all that grit on the chain.  The chain was not coated in oil either.  It was not dry.  But it sure was not wet with it.  I backed the truck out took off the water pumped and flushed block and such out. Then pulled it back in and removed the cover.  So to me it should have been wet with oil.  Inside of the cover is coated with it also.

Oil pressure is good.  I use good oil and wix filters.  The extra long ones also.  So this was like wow to me.  But it could have been done before I got the truck.  The engine needs to be redone.  I will clean it up and put a new chain in it.  See what happens.  If that does not fix it.  Then it is done sadly.  I am going to start it up and see if any oil is getting to the chain before I remove the old one. 

The ignition modules.  All the 3 of them would of had to be bad.  One I started with,  Replacement,  And replacement again.  All 3 by different companies.

Also.  ESC?  I have not heard of that.  Or I call it something else.  This 85 does not have a computer.  Or spark knock control.  The computer fried out.  And the distributor was all dry rotted.  So I just went back with a vacuum advance one with the HEI only.

Thanks 

Offline TexasRed

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #3 on: September 18, 2021, 12:17:55 AM »
Have you changed the ignition coil? The module can usually be checked at the parts store. Run it a bunch of times to get it hot. If the coil is bad, it can take out the module in funny ways.

If you do change the coil, just get a bone stocker. The "high performance" ones aren't worth it.

Offline StarrLion

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #4 on: September 18, 2021, 12:27:41 AM »
Thank you.

Yes I did.  I had a new cap, rotor and coil for another truck I put on it.  Second time to just make sure it was not it.  I took it off the other working truck and did that.  Did a swap since it was going there anyway.  Still same problem.

And yes you are correct.  After so long I change them all out.  Only bad thing about the HEI.  Is they over heat and bam.  It just dies.  Or you go to start it again.  And nothing.  Had one long ago go in and out of me before I knew much about them.  When it finally died on me.  Then I found the problem.  LOL 

Offline TexasRed

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #5 on: September 18, 2021, 12:44:35 AM »
What about the grounds? It sounds weird but that can sometimes cause issues because the factory ground can go through the alternator bracket and that was fine back in 1984/1985 but rust does eventually form.

Online VileZambonie

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #6 on: September 18, 2021, 07:53:57 AM »
Before you fire the parts cannon again, go back to the preliminary checks you missed:

1) Perform a visual inspection on your fuel hoses and ensure none of them are kinked or collapsing. Perform a fuel volume test as well.

2) Perform a compression test with a battery charger connected, choke open, ignition coil disabled, wide open throttle. Record each cylinder's results.
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Offline StarrLion

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #7 on: September 18, 2021, 10:20:30 AM »
Thank You.

The ground to the bracket was fine.  I was wondering about the bracket to the engine though when I was removing it.

The fuel pump flow was very good.  Pressure was also fine.  Line are fine.  I even blew air through them to make sure.  Gas tank is not that old.  Replaced all rubber hoses on it when I changed it.

I have not did a compression check. 

Offline bedwards

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #8 on: September 18, 2021, 12:19:21 PM »
There is a ground on the coil frame itself, make sure its there. The electronic spark control is in a module above the glove box. If you have a 5 wire module in the distributor, then you should have ESC. They are prone to failure although I still have mine connected and it works.

Offline StarrLion

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #9 on: September 18, 2021, 02:16:54 PM »
Thank You

I thought that was what you was talking about.  That went bad right after I got the truck.  So I just got a new distributor with that not on it.  And just went to a basic system that was on my 77 truck I had.

If someone else is reading this.  I just tested the oil flow to the timing chain.  For it looks like the chain is not getting good oil.  I ran the engine for a bit.  Not to long seeing how the cooling system is off of it.  But long enough it should have had.  I thought.  Oiling the chain.  Nothing.  Revved up the engine a few times also.  Nothing.

Maybe this is normal?  I am not sure.  I never have seen time a chiming chain this dirty and gritty before.  Just wore out ones.  But they was all clean. 

Oil Pressure is at 40 psi.  The chain was also coated in so much slag I had to spray cleaner and scrub it to find the timing marks on it to see if it was lined up.

Just wondering about this.

Thanks

Offline TexasRed

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #10 on: September 18, 2021, 06:19:17 PM »
I believe the timing chain is a splash system or drainback from the what the valve train gets. At least it is according to: http://www.clubhotrod.com/engine-talk/42157-timing-chain-lubrication.html

So it doesn't get sprayed in oil. However, I don't think this is your issue.

Do you have EGR?

Offline StarrLion

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #11 on: September 18, 2021, 06:49:36 PM »
Thank You for helping.

Yes.  EGR was the first thing I checked for it acted like it was sticking open. 

So you do not believe the timing chain is not out enough to cause a problem?  I should have measured it.  Not having a new one for at least 21 years since I owned it.  I just figured it was done.  And causing the problems.  I was surprised to see it in as good of shape as it was in.

The timing chain gets oil from the splash and from the cam bearing in the front.  I searched for a oil path and found many that shows it comes out behind the cam shaft and drips down on the crank gear.  When I took the gear off this afternoon it was wet behind it.  I just thought it would have been a little more oil come out then it does. 



 

Offline JohnnyPopper

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #12 on: September 19, 2021, 02:09:57 PM »
Try running her with the EGR disconnected.

Chain is oiled by the front cam bearing for the most part.
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Offline TexasRed

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #13 on: September 19, 2021, 11:32:12 PM »
Other things to check are the PCV valves and the charcoal canister.

Offline StarrLion

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Re: 305 Not Running Correctly. Unable to find problem.
« Reply #14 on: September 22, 2021, 08:34:03 PM »
Thank you everyone.

Update:  New timing chain fixed the problem.  Engine has its power back with no miss fires, stalling or anything like that.  I put a colyes chain on it.  It was tight.  No slack at all.

As to the ones that posted.  I did change the PVC.  And I did block off the canister.  I have had them cause problems before.  I had one go bad and fill the carb up with charcoal or what ever was inside of that thing.