Wrong forum I know

GoBears · #1 03-12-2009, 11:14 AM

Hey everybody. I know this is the wrong forum for this problem but I trust you guys more than anyone else on here. If there is something you have to say about this I would like to hear.

I have a 93 Blazer with the 4.3 vortec. One day it was kind of hard to start. Two days later it wouldnt start at all. Would just turn over and over without even trying to start. A small shot of wd40 into the intake and it fired right up. The fuel does make prime sound at key on. Basically just doesnt get any fuel at startup but once started it runs great. No misfires, no loss of power and the fuel economy is fine also. If its been running a bit I can shut it off and will start back up on its own. Once it sits for a few hours tho it wont start again. I'm leaning towards the FPR going bad.

Since my GTP is still down with the transmission and money being so tight, I'm trying to get all the feedback possible before throwing money at this vehicle.

Thanks so much
Jeff

BNaylor · #2 03-12-2009, 11:20 AM

No problem. We will allow the post.

What is the fuel pressure reading? Is it in specs? You should be able to check it even on the 4.3L engine and possibly tell if the fuel pressure regulator is the cause. And how fast does it bleed off? Also, there should be a one way check valve at the fuel pump in the pressure line.

GoBears · #3 03-12-2009, 11:34 AM

Yes there is a valve on the fuel line behind the plenum which I'm pretty sure I can check the pressure. I haven't got a fuel pressure gauge. I hope this can be rented at advance. If not how much do they cost? I am going to try to get there today and get some readings for you.

Thanks
Jeff

BNaylor · #4 03-12-2009, 11:45 AM

Probably a good investment and you can use it on your GP. Most parts retailers do not rent them but sell the gauge outright. You can get a good Actron (CP7818) brand for around $40 with lines, connectors and it has a bleeder to get more accurate readings.

Just to be sure check with Advance.

richtazz · #5 03-12-2009, 01:57 PM

I agree with Bob that checking fuel pressure at key on/engine off would be my first step. If they don't rent it, they sell that fuel pressure guage Bob mentioned at Advance (I used to work for them).

Fortune50 · #6 03-12-2009, 05:39 PM

As a quick initial test, why do't you swap the fuel pump relay with another relay that looks just like it in the fusebox and see if it makes any difference.

BNaylor · #7 03-12-2009, 05:59 PM

Quote:

Originally Posted by Fortune50

As a quick initial test, why do't you swap the fuel pump relay with another relay that looks just like it in the fusebox and see if it makes any difference.

If he can hear or detect fuel prime prime why? See Post #1.

Quote:

Originally Posted by GoBears

The fuel does make prime sound at key on. Basically just doesnt get any fuel at startup but once started it runs great.

Fortune50 · #8 03-12-2009, 06:38 PM

Quote:

Originally Posted by BNaylor

If he can hear or detect fuel prime prime why? See Post #1.

Well since it's such an easy thing to do and potentially free, I suggested he do that to rule it out

. I had a buddy at work w/ a '99 S10 Blazer have a hard start issue and even some running issues, and I remember he had said he replaced the fuel pump's relay, but I admit I don't remember if it fixed his problem or not

. Sorry if I seemed to throw an idea on the table that seemed unnecessary

.

tblake · #9 03-12-2009, 08:28 PM

the early 4.3 vortech's had problems with the CPI injector/poppet valves. I've seen some that would leak externally, causing 3 cylinders on one bank to run rich and the other 3 to run lean. I remember being able on some of them to remove the throttle body and have a peek inside to look for washing. (this was on later 4.3's. I think yours this may not work). Also 4.3 vortechs have slightly higher fuel pressure in order to open the poppet injector nozzles. If the pump is weak, it will not supply enough pressure to open the valves.

I'm agreeing here with the other guys, best to start with a fuel pressure check. I'm betting your problem is fuel related.

old_master · #10 03-12-2009, 09:40 PM

Guaranteed it's a fuel delivery issue. Key on, engine cold and not running, fuel pump running: pressure must be 60psi to 66psi. Must remain above 55psi for 3 to 5 minutes after the fuel pump shuts off. If it fails this test, it means there is a fuel delivery problem, it does not tell you WHAT the problem is, only that a problem exists. Post your results and we can continue. Harbor Freight has a fuel tester for $12.99 and it works fine.

BNaylor · #11 03-12-2009, 11:39 PM

Quote:

Originally Posted by old_master

Harbor Freight has a fuel tester for $12.99 and it works fine.

With all due respect to you my friend the fuel pressure tester from Harbor Freight Tools is a piece of crap to put it nicely. Inaccurate and suffers from gross quality issues. I wouldn't recommend it to any of my enemies.

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