I'll chime in late and say that's your problem. I went through the same headache on my enigine until a friend told me to adjust the valves since i had the head worked on. Quick adjustment and it fired right up!

 

fingers crossed indeed! I'll try to find that pm you sent me months ago and read up on the process.

 

hey speedy- mine is starting fine but I can't get it to rev above 1800 rpm, regadless of where the distributor is located. Feels more like an electronic limited than mechanical. I would think that if the valves were way out of whack of would run like crap when i rev it up, but this isn't the case. It actually runs smoothly up until the "limiter" knocks it back down to idle.

 

Well, adjust the valves and you'll know, I guess.


Here's some good info...
https://www.yotatech.com/forums/f116...stment-135452/

If you can't find the PM, let me know. I've got it in my records somewhere's.

 

So it starts just doens't rev above 1800rpm...just something simple to check is the plug to the mass air. Mine was not fully connected b/c I had hit it while working on my truck and i couldn't even tell it was halfway unplugged(mine did not have the metal clip to hold it in place) Pushed it back on and had my truck back to normal.

 

Thanks for the input. The MAF sensor plug is on good.

Background - The truck idles "okay" definitely not good. For reference, the gear shifter in the cab shakes all around. It used not to do this. However, when I rev the engine (until it cuts out) it becomes smooth.

So tonight I pulled off the plug wires all of the time. Each time it would about kill the truck when I would pull the wire, except for plug wire 4 (of course the one at the back). When I pulled this wire nothing happened. However, I put it close to something metal and it was arcing just fine. I even put on a different plug wire to make sure it wasn't that. Now when I would go to rev the engine up, the roughness would not go away like it did before, which leads me to believe that cyl 4 isn't firing until I rev the engine at which point it does. Talk about making things difficult. So I've pretty much established that I have spark. Must be a fuel problem. Not sure how I'm going to figure this one out, but I guess I can try trading injector 4 for injector 1 and see if that's the issue. Looking forward to pulling that intake manifold!

Which brings me to my next point - When the engine was cold it would rev well over 2000 rpm (I only had the heart to rev it to 2500 cold) without cutting out. As the engine warmed up, the "rev limited" slowly migrated down to it's 1800 "warm limit". Anyone have any more ideas on this one?

Also, unfortunately the engine still has no codes stored. I'm surprised about that, as I would have thought pulling a plug wire would throw a misfire code, but maybe these old rigs don't look for that.

 

Well, put in my 2 hours worth tonight. Pulled the upper intake manifold and fuel rail. Swapped injector number 4 with number 1. Checked the wiring harness leading to injector 4, and it checked out okay. Went ahead and sprayed hte injector down with carb cleaner for good measure.

Slapped it all back together and it started up. Sounded like before.. a miss. So, pulled plug 1 and the truck coughed and began to die. Darn. (or good) Pulled number 4 and no change. Just like before. So, I've pretty much ruled out that the injector is bad, because, well, obviously I swapped it out. Yes that spark plug wire is delivering spark. What gives??

 

If it's not the injector or the plug, I'd have to say it's either ring related or valve related and you're not building compression. Have you tested the compression?

I know I said "I'm all out of answers" (in the PM), but I just thought of that when I read the recent post....

 

Have not tested compression Matthew. But if compression were bad, how would it rev smoothly as though number 4 is working when I give it gas? Also I still have that whole pulsing rev limiter issue to solve...

 

Did you get the valves adjusted?

 

I don't know enough about the rev limiter to give any input on it. I do know it's connected somehow with the ignition circuit. I'll have to read on it.

But.... the motor can rev more smoothly because you have more power to push the one piston around......even thought it's lazy/dead.....as you give it more gas. More gas means more horsepower created through combustion. I tell you....when I had a dead cylinder in my V6, the only way I noticed it was at low RPM/idle and the lack of power under load. I went all around the motor looking elsewhere other than the one burned valve that was my problem. Not saying you have a burned valve, but if it's too tight or otherwise, then you have a problem.

All I'm saying is, that you have only three reason a piston is not pumping.....if it's actually not pumping. Two reasons you've already eliminated. So, it has to be the third.....compression. Unless, you have a problem with #4 injector wire. In which case, it won't hurt a thing to put #3 wire on it, if you can get it to reach over.

 

No, I have not yet adjusted the valves abe. I suspect this COULD be the culprit. Matthew- there is no difference in the way the engine idles with or without the spark plug wire on number 4. HOWEVER there is a very noticeable difference in the way the engine revs up with and without spark plug 4 hooked up. Without spark plug 4 hooked, the engine revs about like it idles. Poorly. With the spark plug attached it revs nice and smoothly.

 

Okay. So, you're getting combustion on #4. I'd try adjusting the valves then. We atleast know that's not been checked and addressed. Get that out of the way and, if you have to, move on to the next fun thing.....

I'll give you a call from work today......sometime after 1pm.

 

Found this on rev limiter....

http://www.autoshop101.com/forms/h43.pdf

Don't know if it has anything to do with what's going on, yet. I'll have it read by this evening.

 

If the valves aren't adjusted properly they don't open and close when they should and may get stuck open if the adjustment is too tight or not open far enough if the adjustment is too loose.

 

Any progress?

 

Not tonight. Tomorrow around midday I'll be checking the compression. Matthew is going to come over and put his big brain to the test as well later in the afternoon. Hopefully we'll have a good update tomorrow!

 

If you want, I'm willing to teleconference with y'all. PM me and I'll give you my phone number and we can brainstorm together. I really want to help you get this working.

 

It's up to Kyle, but I'm down with that idea. PM me your # and I'll keep it handy if we can't resolve it.

 

Thanks Abe! If Matthew has your number, we might just do that if we can!