Hey guys,

So a couple of weeks ago while driving I came to a stop and the truck just died on me and would not start. Had it towed home to begin looking into the issue.

I have swapped the fuel filter to eliminate a possible blockage, still no luck. Currently I can get it started as long as I do not have the brake depressed. While the coolant is still cold, if I hold the brake it dies. Without the brake depressed she idles fine and I can rev the engine.

Once the coolant warms up, I can press the brake without it dying, however if I pump the brakes it will start to bog and kill the engine. Without touching the brakes after warming up it idles like crap but I can rev it up and runs strong.

Had codes 6,7, and 11. OHM tested the air flow valve and TPS (which the code points to) and came back good. I have loosened the screws on the TPS and moved it back and forth and will notice the idle change but still won't idle where it should. I have swapped the cables, distributor, and rotor with no luck. I will say I know my vacuum lines need to be replaced but in the past that would cause the idle to go up or surge, not bog the engine down and kill it. Bought a timing light and checked the timing which said it was at -12 TDC, adjusted distributor cap and TPS to bring it back to -5, however, I did read somewhere that if you jump the terminals the idle should drop when its in timing mode, and mine does not drop in idle.

If anyone has some suggestions I'm open to hearing them because I am just banging my head on the wall trying to figure this thing out. Can post pics or possibly even a video if it will help. Thank you!

 

Sounds like your brake booster might be allowing extra air into the engine causing it to stall.

How do the brakes feel??

 

How does the electrical system under the hood look, any corrosion?

My 85 had a similar problem, where it had a hard start and using the brakes would kill it. I replaced all kinds of crap. It eventually was no-start, so I cleaned all the grounds I could find and it ran fine after.

Also, the TPS is real sensitive. You should use a multimeter to set it within specs or it can make the truck run bad. You can just unplug it and the engine will run in open loop mode. Check 4crawler's site for more info on this.

 

@wyoming - brakes feel good, and did the test I read about where you hold the brake and try to start it and feel if the pedal depresses and it does so seems like brake booster is good, but could be wrong.

@gsp - Before I bought the thing I know there were electrical issues that my buddy told me about, but has been running good for over 6 months then this happened out of the blue. I did notice one of the grounds (the one from the battery to the fender) is broken. Could that cause this issue even though there are multiple other grounds?

As a note, I did notice when I attempt to drive it, it seems to die after say I go over a speed bump. Possibly the wiring to the fuel pump shorting as the body moves back and forth? Ordered a TPS because after using some alligator clips I did notice that my VC-E2 with closed throttle I couldn't get below around 12-1300 ohms and 4crawlers spec calls for 200-800. That should be here sometime today so will probably have to wait until tomorrow morning to swap it in.

 

Hey guys,

So I ended up figuring this thing out. Ended up being a bad ground going to the fender well. Decided to swap it out just because it needed it and sure enough it fixed the problems I was having.

 

Good to know. Thanks for the follow up. Those grounds can play havoc.

 

Also glad to hear it worked out. Sounds like you had a the same problem I had. Even a small amount of corrosion on a ground wire can cause an intermitent broken circuit, which makes diagnosis harder.