truck missing

[tarheelboy]

OK. This is my 3rd Dodge forum. Nobody seems to want to help anybody if you haven't reached 1000 posts. Anyway I need some help figuring this out. I have a 1989 Dodge W100, automatic, 318. After the truck has warmed up, if I accelerate hard at all from a stop, the truck misses, surges and cuts off. If I accelerate very lightly it does just fine. Once I am up to speed, 25mph or so, I can accelerate as hard as I want to and it responds just fine. The problem is only when I accelerate hard at all from a stop. This happened about a month ago. I changed the plugs and wires and the problem went away. Now it is back. I have also changed the o2 sensor and catalytic converter. Please give me some ideas to try. Thanks.

[Batman]

An '89, huh.  Well, that's just going back to old school.  I believe that is still a carbureted engine, is it not?  Assuming you do have a carburetor have you rebuilt it and re-tuned it lately?

[Smitty]

Have had similar problem in past...ended up being fuel pump.

[lilfroger]

Being that it's a 318 have you looked at the plenum?  Any loss of oil? Any idle issues?
http://www.dodgeownerforums.com/smf/index.php?topic=9504.0


Before completed on the '99 we had issues with throttle response was one of the issues; push the peddle and no love But after it was a happy beast.  Also fixed so many other issues.




Oh and don't worry about those other places   You've found a happy place now (OK happy as long as you like a few crazies)  You'll find we're a good group.

[Tom Courtright]

89 iirc has a throttle body injection setup? Does sound like a fuel pressure problem.

[Batman]

Ok, did a little more digging (Call is Google research).  For '89 that 318 should be a throttle body injection engine.  So, disregard my carb question.  The fuel pump is a darn good question, since it is an injected engine any disruption in fuel delivery from the pump could cause your missing and shutting down issue especially in a high demand situation like romping it from a stop light.  The intake design on your engine is the much older rev and shouldn't have the belly-pan issue, that is mostly for the later engines with the cool "beer barrel" intake.  But, it certainly doesn't hurt to check for vacuum leaks, since those can cause pesky issues like you describe when warmed up.  A leak between the intake and head would be pretty common, my favorite way to search for that is let the engine idle, then spray carb cleaner along the interface of the intake to the head, if you hit a spot where the engine revs up you just found your leaky gasket.  Other typical areas for a vac leak are the rubber line to the brake booster and the rubber lines that go from the manifold to your HVAC controls.

[tarheelboy]

Thanks for the replies guys. So you think maybe it was just a coincidence that the new plugs and wires fixed it right away but not for good? Oh, I should also mention that I am by no means a mechanic. I have a Hayne's manual and some tools so you may have to dumb things down for me. anyway I will try the carb cleaner test for a leaky gasket and check hoses for vac leaks and post progress.

[Buford445]

Did you replace the coil with the plugs and wires ? Just a thought

[tarheelboy]

No, I didn't replace the coil. Just the wires and plugs.

[kenz]

Okay, not sure exactly what kind of ignition it has, but thinking that if it were a traditional design, maybe the advance isn't working/stuck? Seems to me if I remember right, the ignition would advance at low rpm full throttle until up to rpm, like 2000rpm. Replacing the wires may have jarred something making it work for awhile.

This is coming from a very old file in the memory bank, so I may be way off.

[Batman]

I'm still thinking it's more likely a fuel issue.  Fuel issues are very prone to showing up based on load/demand.  Spark issues are generally very easy to spot at specific revs regardless of load.  But, doesn't hurt to cover all the bases while diagnosing, did you replace the cap and rotor along with those wires and plugs?

[Smitty]

I'm still thinking it's more likely a fuel issue.  Fuel issues are very prone to showing up based on load/demand.  Spark issues are generally very easy to spot at specific revs regardless of load.  But, doesn't hurt to cover all the bases while diagnosing, did you replace the cap and rotor along with those wires and plugs?

Yep...hook up a pressure gauge to the fuel point under the hood and drive around. See if the pressure drops off. How I found my problem.

[tarheelboy]

I'm still thinking it's more likely a fuel issue.  Fuel issues are very prone to showing up based on load/demand.  Spark issues are generally very easy to spot at specific revs regardless of load.  But, doesn't hurt to cover all the bases while diagnosing, did you replace the cap and rotor along with those wires and plugs?

No I didn't replace them. I inspected the cap for cracks but it looked ok to me. They are not expensive so maybe I'll just change them. I figured if it was missing from a spark issue then it would miss through the entire driving range not just upon acceleration.

[tarheelboy]

I'm still thinking it's more likely a fuel issue.  Fuel issues are very prone to showing up based on load/demand.  Spark issues are generally very easy to spot at specific revs regardless of load.  But, doesn't hurt to cover all the bases while diagnosing, did you replace the cap and rotor along with those wires and plugs?

Yep...hook up a pressure gauge to the fuel point under the hood and drive around. See if the pressure drops off. How I found my problem.

may be a dumb question but if the pressure gauge is under the hood how will I see it while I drive around?

[Smitty]

I'm still thinking it's more likely a fuel issue.  Fuel issues are very prone to showing up based on load/demand.  Spark issues are generally very easy to spot at specific revs regardless of load.  But, doesn't hurt to cover all the bases while diagnosing, did you replace the cap and rotor along with those wires and plugs?

Yep...hook up a pressure gauge to the fuel point under the hood and drive around. See if the pressure drops off. How I found my problem.

may be a dumb question but if the pressure gauge is under the hood how will I see it while I drive around?

LOL...true...get long enough rubber hose so you can see gauge while driving.