3800 SC Fuel Pumps (Page 1/1)
hnthomps SEP 21, 02:59 PM
What specific fuel pumps have successfully been used in 3800 SC engines on a long term basis? My engine is a Series II that has a 3.4" pulley. This vehicle likely needs a new fuel pump after sitting at a paint shop for more than two years. The engine will start with starting fluid but will not run on gasoline. No pump priming sounds are evident when you attempt a start so the pump is a prime candidate for the issue.

I would really like to reclaim the car but need it in running condition to load on my trailer and make it into a 90 degree turn to my basement garage.

Nelson
Vintage-Nut SEP 21, 04:31 PM

quote
No pump priming sounds are evident when you attempt a start so the pump is a prime candidate for the issue.



Check the fuse and relay first
Second, try putting fused +12V at the ALDL 'G' connection which will run the fuel pump without the relay...


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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 09-21-2025).]

Raydar SEP 21, 08:32 PM
After verifying power, here's something else to try...
You know about where the pump sits in the tank. Whack the bottom of the tank, where the pump rests.
This should NOT be considered a "fix", but it might allow you to accomplish what you need to do.

Sounds like a great paint shop. But at least nobody parted it out. (IYKYK.)
Dennis LaGrua SEP 27, 11:42 AM
Most effective way to check fueling is to attach a scanner like HP Tuners to the OBD connector so that the STFT and LTFT can be measured at a number of RPM points. For WOT its best to use a wideband O2 sensor shoot for about a 12:1 A/F ratio and monitor fuel pressure. These require extra gauges but what is your engine worth?
I have almost the exact same setup that you are running. I have been running a Bosch fuel pump made for an LT1 and its always kept up.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Jay-ID OCT 03, 05:11 PM
I'll share my experience with fuel pumps and the 3800sc. I started with a knock-off Walbro 255 lph. It failed within a year (back in 2009). I had a shop helping at the time and they recommended the stock Grand Prix GTP pump. That pump lasted fine, but it turned out not to support my moderate upgrades (cam, 3.3 pulley). The pressure wasn't quite high enough at idle and the pressure would fall off at WOT. In 2023, I upgraded to a Deatschwerks 340 lph advertised for a BMW (with 9-1031 Install Kit). While not a direct fit, it installed easily. Now my idle pressure is good and it doesn't fall off at WOT.
Dennis LaGrua OCT 03, 05:30 PM

quote
Originally posted by Jay-ID:

I'll share my experience with fuel pumps and the 3800sc. I started with a knock-off Walbro 255 lph. It failed within a year (back in 2009). I had a shop helping at the time and they recommended the stock Grand Prix GTP pump. That pump lasted fine, but it turned out not to support my moderate upgrades (cam, 3.3 pulley). The pressure wasn't quite high enough at idle and the pressure would fall off at WOT. In 2023, I upgraded to a Deatschwerks 340 lph advertised for a BMW (with 9-1031 Install Kit). While not a direct fit, it installed easily. Now my idle pressure is good and it doesn't fall off at WOT.



Those knock off Walbro pumps were really terrible. The AC Delco Corvette fuel pumps are the choice for many 3800SC and other engine swaps. Deatchworks fuel pumps may be manufactured here in the USA, If you must buy Chinese the Delphi product seems to be good

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 10-03-2025).]