I posted this on another site as well so some of you may have seen this before:
Here is a stumper. I brought my truck in to the dealer for fuel tank recal. They said that they could not get the old pump out so they replaced that too. When I brought it home, it seemed fine, so I installed an MSD 6AL that I had laying around from an old project. Shortly after this, I started to have a rough idle after a few minutes of starting- just as the ram startd to become warm to the touch- which turned into hesitation and stalling when any throttle applied. I thought it might be a bad pump but the fuel pressure is ok - increases slightly when throttle is cracked. I have not replaced the ECU, distributor nor the fuel filter (I thought it might be a saturated coil or bad amp but don't think so) I will try to do the fuel filter ASAP.
But, the block was junk so I pulled it out and bough a new 4.0, threw in a hotter cam, temporarily ignoring the hesitation problem. I got the thing back together with new O2 sensors, TPS, coolant temp sens, 1yld fuel temp sensor, IAC (NAPA GM version), pro cleaned injectors, H20 punp, tranny cooling lines, etc. set timing and base idle (vac >15 + no indication of leaks)- of course, the hesitation is still there. If I can get past the initial opening of the throttle, it runs strong. But, if it stalls, it will not start again for 20 min. How reliable are the fuel temp sensors? Would it be weird for one to go within a year?
I did reset the base idle again after a good warm up and it needed a lot of adjustment. The adjustment bolt is almost bottomed out and it is still a bit high.
Any thoughts on what would cause the hesitation/stalling/ hot start issue?
Here is a stumper. I brought my truck in to the dealer for fuel tank recal. They said that they could not get the old pump out so they replaced that too. When I brought it home, it seemed fine, so I installed an MSD 6AL that I had laying around from an old project. Shortly after this, I started to have a rough idle after a few minutes of starting- just as the ram startd to become warm to the touch- which turned into hesitation and stalling when any throttle applied. I thought it might be a bad pump but the fuel pressure is ok - increases slightly when throttle is cracked. I have not replaced the ECU, distributor nor the fuel filter (I thought it might be a saturated coil or bad amp but don't think so) I will try to do the fuel filter ASAP.
But, the block was junk so I pulled it out and bough a new 4.0, threw in a hotter cam, temporarily ignoring the hesitation problem. I got the thing back together with new O2 sensors, TPS, coolant temp sens, 1yld fuel temp sensor, IAC (NAPA GM version), pro cleaned injectors, H20 punp, tranny cooling lines, etc. set timing and base idle (vac >15 + no indication of leaks)- of course, the hesitation is still there. If I can get past the initial opening of the throttle, it runs strong. But, if it stalls, it will not start again for 20 min. How reliable are the fuel temp sensors? Would it be weird for one to go within a year?
I did reset the base idle again after a good warm up and it needed a lot of adjustment. The adjustment bolt is almost bottomed out and it is still a bit high.
Any thoughts on what would cause the hesitation/stalling/ hot start issue?
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