TBI troubleshooting

[44th Miss Inf]

Working on an 88 R30 with tbi 454. Truck has sat up a while and I was asked to get it going again, so troubleshooting the tbi system.

So far only thing I have change is the oil switch for the fuel relay, as it was damaged. I know the passenger tank pump is bad, as I’ve jumped 12v to the test Port. Passenger pump won’t run, but hooked up a spare sending unit / pump and that pump runs.

I can hear the selector valve changing, but haven’t had time to check if I have power to the left tank.

Need to put my hands on my spare hot start module and ECM from an 88 7.4/400 truck I had.

It has a blown ECM B fuse, so I’m also checking for shorts and good grounds in the circuit. Once I get fuel sorted, I’ll work on the other bugs in the truck.

Been a while since I’ve worked on tbi systems, so having to reach into the unused files in my head (also have my service manual out)

Going to see what pumps I can pick up local, either the ep381 (96-97 Vortec) or ep377 (95 tbi) I’ve run both before on the tbi systems even though they do have higher pressures. The ep386 (stock pump) just never seemed to supply enough fuel for the 454.

Getting to old to be climbing under a truck or leaning over in an engine bay, lol

[DieselSJ]

That's a good start. I put the EP381 into both tanks on my '87. I was going lean at high RPM with just adding a better exhaust. When you change the pumps, also change the sock on the bottom of the pump to the one that is designed for the EP381 pump.

Change fuel filter.

When you get it running, hit the spray pattern on the injectors with a timing light and make sure it is a nice cone shape and that there is no fuel dripping.

Typically if you hear the selector valve move then the function is fine.

[44th Miss Inf]

I have 2-ep381 pumps and strainers coming along with filters. Local (small town parts store) only had 1 pump in stock, so got them to get me 2 coming, plus I had to go back on shift for a few days.

Got ECM B sorted. ECM was bad. Fuel module is good. Got a bad fuel relay or relay connector. Also sorting other odds and ends.

I’m off this weekend, so will build a “tool” to pull the bed with to change pumps.

Truck is almost a time capsule. 88 conversion crew cab, original paint, 88 or 98k original miles. California truck, so still has all the CA emissions etc.

[44th Miss Inf]

Old post, but updating

Ended up changing both tanks, sending units and pumps, plus put a rebuild kit in the Tbi unit. Got wife to turn the key to check for leaks while I was under it. Climbed out and told her to start it, and she replied “It is running”

Runs great as I’ve put a few miles on her. Got a few things to do to clean up the interior some and that’s it.

[DieselSJ]

Sweet!!

I was chasing a high-idle issue on mine for a while. Found some obscure posting about the pickup in the distributor generating a weak signal. When I data-logged all looked good though. Replaced the dizzy and problem solved!

I know it was the pickup and not the ignition module because I ended up using my old module. Even though this was supposed to be a 'new Delco' brand dizzy, the ignition module didn't have any Delco or GM markings. Truck actually ran like crap with the new dizzy until I put my old genuine Delco module into it. But, high idle issue solved.