OPINIONS / HELP urgently needed!!!

[hokietiger]

Folks, it's me again with the continued saga....I need URGENT HELP concerning my 1989 DODGE POWER RAM "W100" truck (5.2L, 318 c.i. EFI Throttle body with auto trans). Some of you have really made an effort to help and I appreciate it very much!!....Please allow me to summarize again my situation (which includes a few updates from today).

At cold startup, the engine idles nicely for about 20-30 seconds then begins to idle roughly with frequent episodes of a momentary idle drop to near stall. Most of the time it will catch itself and bump back up to normal idle rpm (still rough) repeating the sequence ...but will occassionally stall out....Never a surge upward in idle telling me that a vacuum leak is probably not the issue.

Here is what I've done so far:

1. Rebuilt / cleaned Throttle body with new gaskets and new O-rings for the fuel injectors.
2. New plugs, wires, distributor cap and rotor button, and new ignition pickup in the distributor cap.
3. New Idle control solenoid (adjacent to throttle body)
4. New fuel filter
5. New Air filter and PCV valve
6. New O2 sensor.

Also tested the MAP SENSOR (functions properly) and inspected almost all vacuum lines for leaks....Looks like a new EGR valve has been recently installed.
Viewed the fuel injection into the throttle body barrels while idling. Fuel sprayed evenly into the barrels even
just before the idle dropped and stalled the engine (telling me that a lack of fuel flow may not be the issue).

Ran a "key on-key off" code check and got #37 which indicates:

part throttle lock/unlock solenoid driver circuit (87-89 models) OR, solenoid coil circuit (85-89 Turbo I-IV models).

Wonder if the THROTTLE POSITION SENSOR could be an issue??....I would think that the FUEL SENDING UNIT in the gas tank
may also be an issue but, as mentioned above, I saw NO DIFFERENCE in fuel flow into the Throttle Body barrels when the truck stalled from a drop in the idle rpm.

Again, the truck cranks easily and idles nicely for about 20-30++ seconds at cold startup then begins idling a little rough with abrupt, frequent drops in the idle rpm (almost near stall with an occasional stall). It could still be fuel injector issues because I just don't know enough to be completely accurate.

Also, if I try to immediately recrank the truck after stalling, it is very difficult to restart. However, If I wait about 10-15 seconds, then it restarts easily.

Thanks for all help possible !!

Mike

[AHineman]

If it quits, try turning the key on and off a few times to build fuel pressure before actually cranking it. If it starts easily after that then I'd say fuel pump issue, but IDK.

[hokietiger]

I recently purchased the truck from a "one owner"....It has 91,000 miles and has been sitting a lot (sporadic driving for short distances at best by the owner). You could tell it had not been driven much at all lately. When I test drove it for a short distance (3 miles), non of the current symptoms were evident at that time. The problems developed only after the purchase when I added a can of "Sea Foam" and a small bottle of "Lucas" injector cleaner along with about 1 gallon of gas (tried to up the concentration for a good cleanout). The truck had very little gas when purchased...I've added another $20.00 worth of gas since then.

Wonder if "dirty fuel" or sediment in the tank could be the issue... This morning, she cranked normally and idled very nicely for well over a minute and then I shut her down before any symptoms developed.

Maybe adding MORE fuel now will help with the diagnosis.

Thank YOU for the reply!!

Mike

[dazedandconfused]

I'd fill the tank up completely, change the fuel filter and run it. A simple way to check vaccum lines is to squirt a little starting fluid on the connection. If idle goes up you have a leak.

[hokietiger]

Well, I started her up and after a few minutes, it started the usual stuff of rough idling and near stalling before catching itself ( and sometimes completely stalling)...I viewed the fuel injector gas flow closely under a bright light and noticed a decrease in gas flow when it started to stall. Also, the injectors are making a continuous "girgling" sound.

Is it an injector issue or maybe a "fuel sending unit" issue in the gas tank??

[oldestof11]

Fuel filter. I can almost guarantee it!

[hokietiger]

Sir, I put a NEW FUEL FILTER on it a few days back when doing all the other stuff.....When I rebuilt the Throttle Body, the injectors looked CLEAN. They are old BOSCH injectors with the old Chrysler insignia on the top crimp ring. You could tell the gaskets were original. The O-rings were not cracked or crimpled but obviously seated for a long time in the barrel.

What about the "gurgling" sound I'm hearing from the injectors??....Is that normal??....You can even faintly here the sound with the air filter housing installed.

[dazedandconfused]

I'd drop the tank and check out the pickup. Screen could be clogged. Do you have access to a fuel psi gauge you could put on it to see if you are indeed loosing pressure?

[hokietiger]

No sir I do not have the fuel pressure guage, but I will make an effort to find one and do that.....Please pardon my lack of experience but WHERE would I connect the FUEL PRESSURE GUAGE and the CORRECT PROCEDURE??

Their is also a FUEL PRESSURE REGULATOR (diaphragm looking metal thing plugged into the back of the throttle body.....Other than it's obvious sounding purpose, what is the functionality of this??....How can it be checked to seeing if it's working properly??

Thanks again!!

[dazedandconfused]

There should be a Schrader fitting up around the fuel lines/throttle body. I'd drop the tank and check the filter on the pickup.

[DodgeFreak]

Im pretty sure on the tbi you have to tee into the line on the back of the tb

[jethro]

here is an educated (or uneducated? ) guess .......
you said the injectors sound girgley when it is misbehaving- that sounds like air could be being sucked into the fuel line somewhere. The 20 seconds it runs well sounds like something is "switching" maybe based on engine tempature....
Maybe find the engine temp sensor that the brain box uses and unplug it- or unscrew it so it cant get warm.....
I think most trucks have a feature that bumps up the idle when the air conditioner compressor kicks in- maybe something squirrely there (long shot but worth eyeballing it.....)

OR- as someone else has mentioned--- maybe the 20 seconds of good running is the fuel manifold eating gradualy eating down the fuel pressure which was built up in the manifold before it was started. Once that pressure is depleated - a too low flow cant maintain pressure.

I had a 87 ford which got shellack in the tank and even though it would run mostly fine- there was a thin layer of shellack on the bottom of the tank. If I did not run the truck every day- if I let it set a week- the slight concentration of shellack solution in the fuel would "glue" the impeller (gear) in the high pressure pump. In that failure mode- only the low pressure in-tank
pump would be running- it was only about 5 psi...... so it would start as many times as you tried --- but it would only run about 1/4 second and quit. If your in-tank pump is stronger than mine - you may be getting just enough flow and pressure
to just barely run. The injection pump may be glued stationary.
If the previous owner did not run it often and the gas in the tank got old- it could have broken down in the tank.
new fuel DOES NOT fix the problem- the layer of shellack in the bottom of the tank does not dissolve and go back into solution.
Enough will dissolve into the new fuel to stop your pumps though- even with brand new gas.
If this is going on- you have to drop the tank and stick your hand or a paint paddle in and scrape across the bottom and see if
there is a layer of sticky icky gummy sludge. If there is- the lines will have to be cleaned too- and the pumps.
I suggest MEK to loosen the sludge and wipe it out inside by hand......
I have gone through this drill several times.....

Tim