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Vortec 4.3 CPI hard to start

I have a 94 S-10 Blazer 4.3 Vortec CPI "W". For some reason now when I try to start the truck you can smell gas real bad and it won't start, it almost seems like it instantly floods, but once it's running the smell goes away. Also, the fuel pump seems to run longer than it should. It will run until it pressurizes, then when you turn the key off and back on it runs again for 5-

10 seconds as if it never was pressurized. If I use starter fluid, it typically starts right up and idles just fine, and runs just fine under full throttle even. Once it starts it runs like a champ. Very seldomly it will start without starter fluid but takes a few tries. However, if the truck sits for say 3 or more days without being started, it takes about 10 minutes to start even using starter fluid. The first 5 minutes it doesn't even try to start as if it's not sparking, or else it would at least ignite the starter fluid and sputter a bit. This does not occur if it is started daily. I've had a few mechanics say it might be the (spider) injection assembly which I've seen online is prone to leaks. I've had one say it might be a leaking injector, or the fuel pressure regulator. It sure seems like it's flooding because of the long time it takes to start but if it was leaking fuel into the engine the fuel would combust and blow back I thought but this doesn't happen. I'm at a complete loss with this, hope someone has some ideas.
Reply to
synnyzter
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The injector and nut kit should be replaced. One or both are leaking into the upper intake causing the flooding condition and low fuel pressure. If it's the injector/regulator assembly, it's best to replace the "nut kit" (this actually is the kit containing the 2 fuel lines inside the plenum) while you're in there. If it's the "nut kit" and you can afford to replace the injector/regulator assembly also, I would as it's likely not far behind. Easiest way to determine the failure is to pull out the valve on the top of the engine, it's called the Intake Manifold Tuning Valve (IMTV), and shine a light in there. If the driver's side is wet with fuel, it's the nut kit, passenger side is the regulator. As I said though, if neither has been replaced, do both anyway, and a Hayne's manual should have enough info do make the repair yourself.

Task should take about 4-6 hours for a rookie shadetree to do, not really hard, just time-consuming. I did it myself, before that the most I had done was changing spark plugs. Labor will be about 50% of the cost at a shop, if both parts are replaced.

The mechanics are partially right. The >I have a 94 S-10 Blazer 4.3 Vortec CPI "W". For some reason now when I try

Reply to
Mike Levy

That's pretty much what I figured from researching the internet. For awhile I figured it was electrical but I tested that and the plugs are sparking, I was sure hoping it wasn't the injector assembly because I've already checked the prices awhile back and I don't like it lol. Anyhow thanks for the fast response, much appreciated.

Reply to
jasonb.

If you determine the regulator is the culprit, I've seen just a replacement regulator on several sites. Autozone online shows a Motormite replacement #55162. I don't have any personal experience on how successful a "fix" this would be but might be less costly way to try. If you can afford to do so, replace the nut kit too.

Reply to
DonW

Parts of the injector assembly can become very brittle with age, especially after heat/cool cycles. When I did mine, the locking ears for some of the poppet nozzles broke right off when I went to remove them, and I was being careful despite having a replacement unit. That becomes a fire hazard should the poppet nozzle pop out of its desired position. That's why I suggested replacement of the unit, this way he doesn't have to worry about breaking the poppett nozzle tubes when attempting to repair the regulator.

It is possible to make the repair as you mention, but even GM lists the part as non-serviceable. I imagine it's for the reasons listed above...

Reply to
Mike Levy

Reply to
rrrssm via CarKB.com

replacement

In fact one of the ears broke on the poppet nozzle when I replaced my CPI unit. It's been awhile since I've had it apart but it seems like the regulator could be removed without actually removing the CPI assembly. However, as you stated, one "bump" of the fragile tubing could make the job a nightmare.

Reply to
DonW

I took my Blazer to the shop yesterday to have it checked. It turns out the fuel pump was only pushing at 28psi and the plugs were fouled badly. They are replacing the pump since I already paid to have it towed there and will check the sending unit as well. Total if sender is bad is $465, or $300 if the sender is good and doesn't need replaced. I just find it strange that I just replaced that pump and sending unit sometime around Thanksgiving and it went bad already. Thanks for all the feedback and help guys.

Reply to
jasonb. via CarKB.com

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