hookerpilot47

akwheeler

Just for a quick old school test, when it's running crappy pop the gas cap and see if it clears up.

hookerpilot47

akwheeler

well, if you tell us all the symptoms it will help, but it could be a separate issue. you listed a ton of stuff you replaced, did you test anything or just throw parts at it?

akwheeler

While you are at it some things you didn't mention that you could replace are the distributor cap and rotor, plug wires and fuel filter.

hookerpilot47

I replaced the distributor cap, wires, spark plugs coil. verified no leaks in the intake system on hoses, cleaned cold start injector, replaced full pump because it failed initially in the tank as well as the fuel filter. Changed the oil to make sure i has no transfer from oil to fuel or vise versa. got rid of ear system with blocking plates and covers. tested the sensors for the coolant, verified ports are cleaned and not clogged.

It always starts like a new car in the am, if it is wet or moist or rainy it really goes up and down with idle speed and hesitates hard. IF it it not wet out i can run 30 min or so and then it hits hard like totally fuel starvation and then you can almost hear the injector vibration thru the truck. Hesitates hard, then when i coast to a stoplight it dies most of the time. Replaced the valve on top of the air filter with a rebuilt one ( the one that controls turning on the fuel pump for engine start) helped a little but not if the engine gets hot. Oh yeah cleaned and tested engine coolant temp sensors .

Thoughts ???

Co_94_PU

iTrader: (-1)

Poor run characteristics when it's damp out are a good sign there is an electrical issue, bare wires, poor contacts or moisture where there shouldn't be.

Some of the top culprits are high tension leads (sparkplug and coil wire), and pickup coil in the distributor. Do not overlook the distributor cap's oring.

Poor run characteristics when the engine bay is heat soaked can be electrical or mechanical. Check the compression HOT. Check the voltage drops on primary and secondary fusible links as well as ground wires.

PS. As akwheeler points out the more specific you are about what was tested, the test results and what parts were changed and why. The better a position we are in to help..

akwheeler

I have never been a guru when it comes to engine performance, I have seen issues in the past that caused a time delayed issue similar to yours, clogged fuel lines (curls of green plastic from someone siphoning my gas) and gas caps that don't vent building a vacuum in the tank. Now that you have given more information maybe someone else will chime in with some bright ideas.

Co_94_PU

iTrader: (-1)

You should define the symptoms more in depth.
Surge, lurch, bog... All simple words that are easily taken different by someone not standing next to the vehicle..

I don't see vehicle specs, maybe I skipped over them. what engine? what transmission?

You've had fuel delivery issues before. Which I'll assume means you have a fuel pressure gauge. You are going to want to piggy back this onto the cold start injector line if you haven't already done so. It allows you to see what is happening in real time when the issues occur.

Another thing you can check is if the coil is reliably firing by putting your timing light on.

I still lean to an electrical failure

hookerpilot47

1989 22Re 5 speed 4x4.

Replaced the coil, plugs, wires. I don't have a fuel pressure gauge maybe i need to get one not sure if it would show much till its starts shuttering and hesitating after 30 min or so. I went thru the wiring wire by wire i don't feel its wire but maybe the wire to computer in the right had kick panel. I have no reservations on the coil, replaced but trying to eliminate each system but i didn't need to same exact symptom . Get HOT and then runs like crap.....just hard to describe, dies before you coast to a stop. Hard to start usually takes 5-7 min to start again after it has been sitting a while after getting warm.

hookerpilot47

When i take the gas cap off you can definitely hear the suction that is relieved when you take off the cap. never thought of that wow, well the hesitation happens for a few minutes then gone but then it dies. Good idea

akwheeler

You should hear a whoosh sound when you open the filler cap. What I stated about gas caps that don't vent isn't technically correct on modern vehicles. For evaporative emissions the fuel is in a sealed system and the tank should be slightly pressurized. but if the hoses and tubing to your charcoal canister are plugged you could end up with a vacuum in the tank making the pump work harder and harder as it pulls more fuel out until it just can't supply enough pressure to run the engine. after sitting a while the pressure equalizes and it will run again.

Co_94_PU

iTrader: (-1)

So pull the gas cap and test the lines to gas tank, fuel return from regulator, and evap line from canister to tank. You should be able to pass air through these and might hear burbling or trickling. If you don't hear this its a blocked line, semi major issue, if you do have flow go ahead and replace the gas cap or its seal/rubber.

akwheeler

It would be nice to know the time frame involved here, did you replace the fuel pump first? Did this problem start after that? "replaced full pump because it failed initially"

yotaspliffs

I once had a similar issue on a 91' 3.0 that some one had broken into and sabotaged the engine. They had ripped my battery out, cracked a valve cover, sliced up my radiator hoses etc. Needless to say it took me months before I was able to drive it again. I few months after I got it running it would start fine but after driving it for 20mins or more I would have to wait at least another 20mins for it to cool down before I could get it started again. It ended up being bad/partially disconnected fuel injectors. Do you smell gas in or near the engine bay after it begins to die?

skypilot

iTrader: (1)

Ok sounds like its worse when it rains. This would the coil or secondary ignition components. The distributor uses two coils to sense when to fire the spark plug, there is a test for this. If you need one get a "Rich-Porter" brand distributor, that has a better reputation. What also changes from hot to cold is valve lash, did you adjust it or crank down on the adjusters? Have you checked the camshaft for wear? Modern oils and old engines do not always get along. So the camshaft wears excessively.

Indetrucks

Check to see if the TPS is sticking. They don't typically have electronic malfunctions, mostly end up sticking open and not shutting all the way at Idle due to carbon build up etc.
If the truck runs good, with the exception of idle... this is a strong symptom of a sticking open TPS.

You can test it many ways.
First, check the timing at idle. If it's more than 7 degree's before TDC.. that could be the TPS.
If you jump the diagnostic plug and the idle doesn't drop to 750RPM, that's another indication. You could go old school and do the Ohm meter test on the TPS itself, but that will take a bit of time.
This link shows how to check/adjust the TPS.Symptoms of a bad or mis-adjusted TPS include:

• Inability to correctly set base ignition timing:
  • i.e. you jumper the timing check connector and the idle and timing don't change
• Varying idle speed, unstable idle or even mis-firing at idle:
  • This can happen because if the IDLe-E2 contact closure is not detected, the ECU is "running the engine real slow" vs. entering the stable idle mode. At low RPM and load, all the typical ECU sensor inputs may not be accurate and the ECU is trying to guess what is going on and adjust engine parameters on the fly. In normal idle, the ECU likely has a sort of pre-programmed loop it enters and ignores a lot of the sensor "noise".
  • Note that a low coolant level can affect this as well, if air pockets reach the temperature sender, the ECU can get false readings of engine temperature and alternate between cold and warm idle speeds.
• Hesitation while accelerating:
• Poor fuel economy:

Hope this helps!

hookerpilot47

Thanks that the only thing I have not checked, but fixed the other issues .......Charcoal canister was not allowing the fuel tank to equalize the pressure going to the engine...... can you believe that crazy....... had not had a issue in a few weeks but it does randomly hesitate to start once a while after it warms but nothing like before. what a pain in the ass.

hookerpilot47

Will take a look at it. never thought of that