Hello all!

I have a problem with my 1994 Truck’s 22re engine. I have a video that highlights the issue very clearly and may post it on YouTube if it helps explain things more thoroughly.

The problem is that the truck will only start sometimes, that is it will run perfectly fine and idle and rev like it should. The other times when it is not running it’ll run for approximately 3-5 seconds depending on what you do. If you press on the throttle while it hovers at 900rpm then the truck will die just about instantly; if the let it idle out it will just slowly decline from 900rpm to 0 in about 5 seconds. That is my problem.

I have read other threads talking about MAF sensors or vacuum lines or Air meter sensors and those all make sense but why would my truck randomly start up perfectly with no problems like it was brand new? I have made sure the fuel pump works good and in the process of getting a new fuel filter (was some old gas in the truck for a year). I have a small hole in the filler neck of the gas tank but that has never affected anything. Finished a couple projects on the truck but never messed with wiring. Truck has a recently done ignition system, valve head & cover gaskets.

Can someone one lead me in the right direction if you have had this problem before? Truck is an inch away from being on the road and this is the biggest problem I need to conquer before that.

 

It didn’t write down half of what I said so I’ll have to sum it up in the reply section

 

So basically what I said what the post didn’t capture was that I have done some investigating about MAF or vacuum lines or Air meter sensors but in my case why would those make sense if my truck can run and do stuff like it should? Does that mean they are dirty? The fuel pump works and the truck recently had the ignition system, valve head & cover gaskets done. So it definitely has compression and ignition down. Fuel shouldn’t be a problem, I am getting a new fuel filter as it had very old rotten gas running through it at one point.

Up for any suggestions just that I find my situation very weird because the truck works sometimes just not all the time.

I haven’t messed with the wiring at all or anything either since all of my work on the truck has been focused on the rear end so that may help clear things.

 

Welcome to YotaTech.

"Starts and runs for a few seconds" is the classic sign of a VAF/COR problem (you don't have an MAF - different technology). Fortunately, it is the easiest thing on your truck to diagnose. Next time it dies like that, jumper FP to B+ on the diagnostic connector (this forces the fuel pump to run with key-on). If it now starts and runs, you've narrowed down the problem.

Why would it be a random problem? Why not? You could have a broken wire in the FC circuit of the VAF, making an intermittent connection. You could have a sticky vane in the VAF. Your COR could just be approaching end-of-life (quite unlikely compared to other possibilities). But all repairs start with narrowing down the location of the problem.

 

Thanks Scope, sadly it just does the same thing as it always has and will quit on me no matter how long or short you run the fuel pump through FP - B+ . Does this mean it’s still a fuel problem or rather something electrical?

 

A little update but recently I have been working on getting the truck safetied (required a ton of work) and almost there so throughout that process I have been doing wrenching to try to figure out my problem. So far I rebuilt the whole throttle body, put new injectors in, cleaned all connections and put dielectric grease in them and it has helped a lot. The only problem I have now is if I turn off my truck it won’t start back up but will stay running if I don’t mess with it; It has before started up after shutting it off but it basically does the same problem where as it’ll stutter and try to start but die. I have tried and fixed many things but the problem still lingers, seeking guidance from anyone who has had similar issues!

 

Have you checked AFM connector with a voltmeter? I had a similar issue after a collision and cold weather, where the spring broke inside, and the flapper door wouldn't open, therefore not giving the ecu a signal for air/fuel. It would idle perfect then die when you did anything or when the vacuum advance closed.