Hey guys, great forum. I have a 1995 Chevy S10 blazer (4.3L Vortec with the Spider (Delphi) injection. My mother is the original owner of this truck and it treated her well over the years. The truck broke down last year in a parking lot (would not start). After it was towed to my house I did some diagnostics and it turned out to be a bad fuel pump. I dropped the tank and installed a new Bosch Fuel pump (Part# 69238) and a fuel pump hanger (the old one was rotted). The truck will now start but after several tries, not like it used to (instant). I am worried I put in the wrong fuel pump. I know these trucks use high psi in the fuel system. few things to keep in mind.....

1-) the spider injection (entire unit) was replaced with and updated version in 2005

2-) the Fuel pressure with ign on is 60 PSI

Does this sound like a bad fp regulator?? Should I take off the upper plenum and look for fuel?? I hope I did not install the wrong fuel pump!!!!

thanks for all the help!!!

 

Does it hold above 55 at key on for 10 minutes?

 

Thanks for the reply Chris. I will check tomorrow. the oring in the fp gauge line was leaking fuel so no way to test properly until i replace it tomorrow. Chris. do these trucks need special fuel pumps??

 

What you didnt mention is the leakdown rate. That's very important. It should remain above 50 for more than 10 minutes.
test for that. Thinking you'll find it's leaking down pretty fast.
Then remove filter and rig the FP gauge to test line from tank for leakdown.

Another test is to cycle through several primes before cranking. If it then starts faster that would confirm it's vapor locking.

 

a lot of aftermarket fuel pumps tend to fail on these things, so do as the people above me said and test the fuel psi again and watch to see that it holds.

if you need a new fuel pump, make sure you go with AC delco/ delphi

 

UPDate, did some testing and here are the results.

pain the **** to start....

-with ign ON only, motor off 60 PSI

-engine started and at idle 52 PSI
-turn engine off, fuel pressure drops to 55 PSI and then slowly CLIMBS to 60 PSI.
-After 15 MIN with engine off Fuel Pressure sits at 59 PSi

Voltage 14.46 volts, idles about 850 RPM, idles very nice, got it up to temp. no engine light. Maybe it something else causing the start issue??
I installed new ac delco plus gapped at .045 R43TS I beleive?

thanks for your help!!

 

Update Part 2:

After 25 min Fuel pressure is at 42 PSI. Ign on the pressure went to 60 PSI and the truck started right up!! hhhmmm??

 

Your bleed down is within acceptable levels, but the fact that it continues to drop is somewhat troubling.

If the pressure jumps to 60psi on the initial key-on regardless of the previous pressure, and it stays above 55psi for 10 minutes after the pump shuts off, then the fuel system likely isn't the source of the problem.

How strong is the spark? Have you tested it with a spark tester or just looked at it?

 

Point of information:
Does working the gas pedal still change the mixture on GM OBDII? I did a search and surprisingly came up with nothing save for one thread on Cad forum where the OP {93 Caddy} complained of having to pump three times to start car easily.
-- Then some idiot {Sorry but I cant STAND misinfo being propagated} said it doesnt work on FI cars, like on carbed cars.
I know for a blooming FACT it works on Ford EECIV - it is well documented -and I've used it on Chevy TBI.
* Pump accel to add more fuel
* WOT to reduce fuel
So I'm wondering if it still works as a stop gap to change the injector pulse width while cranking on OBDII. I tried to find it on my alldata but their procedures are so confused I probably missed it.

UPDATE: In fact it does still apply as late as 2005, according to the GM Owner's Manual
I wrote up a thread on it.
https://blazerforum.com/forum/genera...18/#post473578

 

Injector pulse width (IPW) is indirectly controlled by a variety of sensors. It's been a while since I've messed with PCM tuning. Startup IPW is an open loop type of thing which may weigh the TPS sensor higher than the rest. I don't have the program nor the fuel/spark maps on any of my computers, but when/if I buy HP Tuners, I should be able to answer that question fairly quickly. But you could probably ask on their forums as well. Would be the best source for such information.