89 K5 Idles Fine but Cuts out at Speed

[Glen1978]

Just bought a 89 K5 yesterday with 350 tbi and granny 4 speed. It idles fine and runs fine in granny and 1st gear even at WOT. In 2nd and 3rd you can feel it cutting out when you try to accelerate. I ordered all AC Delco tune up parts from RockAuto but was wondering if there was anything else I should check in the meantime. Thanks

[ChevyTech]

Test the fuel pressure with the engine running.

Here is a thread that may help with fuel pressure testing:
http://67-72chevytrucks.com/vboard/s...d.php?t=375132

[Glen1978]

Well found the gauge with the correct adapter 60 miles away round trip. Went and got it and the (*&$)_#$ TBI adapter leaked like a sieve!!! I tried tightening good, everything. Still leaked. I changed the filter before doing this. Still does the same thing. When you first drive it it doesnt do it. The more you drive it the worse it gets. Im stumped on how to check the fuel pressure. Only thing I know to do it order the filter adapter and try that with the loaned pressure guage.

[Glen1978]

Well update. Jerry rigged up a "T" to go in place of the filter with a schraeder valve and I guess the dang gauge is junk too! The schraeder has a pin to push when the gauge fitting is screwed on but the hose doesnt have anything in it to depress it......???? If you press the pin fuel squirts out. Screw on the hose and NOTHING of course. Gona go to the local Napa in the morning and borrow there gauge. They had one to rent but nothing that adapted to TBI. What an ordeal to check FP.

[Glen1978]

Checked fuel pressure this morning with it running......showed just below 14 psi best I can tell on that gauge. I checked engine codes even though it was not throwing a CEL and it was clean.

[ChevyTech]

It has plenty of fuel pressure, so the next thing I would be suspicious of is weak spark. Coil or coil wire would be the most common. Distributor module failure is a very common problem on these trucks too.

If it has restricted exhaust it should also be causing trouble high RPM in first gear, but if you can't find anything else, consider it.

[Glen1978]

I will get my Ac Delc plugs, wires, cap and rotor tomorrow. If that doesnt fix it then coil is next. Distributor shaft has NO play in it so dont suspect that. Talked to my brother and he suggested the coil was breaking down with heat.

The cap/rotor did have a little fuzz on them so I cleaned/sanded that down and it didnt change anything.

[gmc 2500 4x4]

tbi kits are cheap. i had same problem and the fuel diaphram spring was rotted away.

[speedygonzales]

Distributor module more likely than coil, but the coil is considered a tune up item so both should be changed. Don't forget to clean under the module and replace the heat sink compound.