Engine/Transmission (1994 - 1998) Hit a bump, truck misses

[JeppinHackSaw]

Ok, the weirdest thing.



I still have a slight miss at low RPMs (right off idle)



The weird thing though. . going down the freeway on michigans lovely roads, about 72-75mph I hit a bump and the truck starts missing like CRAZY. Let off, or throttle out of it...



370 injectors, 16* timing, stock plate/afc slid forward.

 

[Missouri Mule]

At this point I have no idea. But it will bring back to the top. :-laf

 

[bmoeller]

Sucking air somewhere? The rubber lines can get dried out and crack or break.

 

[Missouri Mule]

JeppinHackSaw, has it always done this or did it start do this recently?

 

[MMoran]

I had a similar problem; I had been getting in and out of the throttle and developed a miss. I traced it by loosening the injector lines and listening for rougher running. Once I determined which cyl it was, I swapped the injector to rule that out. In my case, it was a copper sealing washer in the injection pump. Mine was a '94, so I'm not sure if your newer pump would have this problem, but it's an idea.

Mike

 

[tp0d]

Have you checked out your fuel shutoff solenoid at all? If the coil or relay is weak and not holding up the plunger 100%, you could be restricting fuel when it bounces on a bump. . or, if the linkage is out of adjustment, and you're not opening the fuel valve all the way, that could do it also. .

good luck

-j

 

[JeppinHackSaw]

It started doing it a few months ago when I put the new injectors in it.

Bratby and Dispatch came over and we set the timing, didn't really change it much.

I'm thinkin maybe I f'd up one of the lines while installing the injectors or somethin? I put stiffer throttle return springs on it, and it seems to help a little bit.

Is there a way I can check if it is the shutoff solenoid?

Also, If I hold the accelerator pedal at a constant 11-1200 RPMs, the truck will miss slightly.

I've cracked lines while doing this, and nothing changes, it just misses worse with the line cracked, and doesn't make a difference as to which injector I have cracked to the intesntiy of the miss.

I've bled, and re-bled all of the lines to and from the pump, replaced filters, yadda yadda ya.

 

[Missouri Mule]

370's have caused stumble at low rpm's. But I believe that was with trucks that still had a stock fuel plate. Missing with fuel plate?



With truck running tie the fuel shut off solenoid rod up and take it for a ride, see if does the usual missing.



To cause the engine to miss (when you hit a bump) something has to be loose.

 

[JeppinHackSaw]

It still has the stock plate in it, pushed slighty forward... waiting on the trans to get done before I pour the fuel to it. . just to save a lil bit of parts damage.

I can already slip the convertor with the stock plate in there, so I dont wanna push my luck.

 

[JeppinHackSaw]

I checked out the fuel solenoid today... after messing around checking it for being loose and what not, hit the key and the plunger stays up and I cannot make it move with my hand or a screwdriver prying on it (move it so it goes down)

Even though I did that, I took the solenoid off and used some wire and wired it open. . truck did the same thing.

Like I said before, I tried putting really stiff throttle return springs on it, that didn't do the trick, I'm kinda at a loss here so are most of my dieselhead buddies that I've asked the question too. .

Any more ideas?

 

[Howard Durand]

I would wonder about possibly loose or worn throttle linkage causing it to oscillate after hitting a rough spot in the road.