4.3 Chevy fuel injection question

[garmasters]

After filling the tank and driving about an hour on the highway, 2002 4.3 Silverado (non-Vortec) lost power, died and would crank good but wouldn't start. Towed it home (where it's quiet enough to hear the fuel pump). Installed a new fuel filter (old one made noise when shaken) and still no start. Got 55+ psi fuel pressure. Pouring a little gas in the throttle body WILL make it start until that fuel is used up. Good spark, plugs, cap, rotor and wires. Engine analyzer didn't show any codes. 100,000+ miles, ran great until this happened. Any ideas????? SWAG's are welcome.

[01SS346]

The spider injection parts would be my first check. It's after the pressure test port. If they are gummed up or leaking that would do it. My S-10 has the 4.3L and I bought it last year and had to do the Spider injectors 1 time and they were done 2 years prior to my buying it. Stupid design.

[bryanwheat]

Usually the spider injector doesn't just go bad and cause the vehicle to not run. The most common thing for them to do is for the regulator diaphram to tear and leak fuel into the intake mannifold. You need to check for codes. You could have a crank, or cam sensor bad, or possibly even the electronic egr problem.

[garmasters]

There weren't any codes, apparently it shot craps and dead engines tell no tales............

[Slowleen]

Water in the fuel tank from the latest fuel up?

[garmasters]

Water in the fuel tank from the latest fuel up?


It wouldn't have taken an hour's driving to show up. Grabbing at straws I put fuel injector cleaner and HEET in fuel tank - no change, cranks without even trying to start.

[bryanwheat]

I'm still going with cam or crank sensor, or you have something un plugged somewhere.

[white01ss]

I'm still going with cam or crank sensor, or you have something un plugged somewhere.


This would be my thought. An ignition control module, crank sensor, etc. When they go bad......they go bad, usually without warning.

[garmasters]

I'm still going with cam or crank sensor, or you have something un plugged somewhere.
Any idea how to test the sensors?

[garmasters]

This would be my thought. An ignition control module, crank sensor, etc. When they go bad......they go bad, usually without warning.

From http://troubleshootmyvehicle.com/gm_cmp_4.3L_5.0L_5.7L/troubleshoot_cmp_sensor_6.php

"When the Cam Sensor goes BAD, it will NOT keep your 4.3L, 5.0L, or 5.7L GM equipped
vehicle from starting. Yep, that’s right... your mini-van or pick up or SUV will crank up
and start. Now, of course, it’s not gonna’ run right. Continued in next page..."

.........so I'd rule out the cam sensor. I think I can dig through this website and get pointed in the right direction: http://troubleshootmyvehicle.com/index_gm_4.3L_5.0L_5.7L/index_of_articles_1.php

[Dman03GT]

If I remember right, 55psi is not enough to fire off the factory spider, needs to be between 60 and 62/63

Yep, just verified it, the poppet on the injectors won't open below 61psi. I bet your fuel pump is failing, even though you hear it prime it's not strong enough to build the needed pressure.

[snm95ls]

After filling the tank and driving about an hour on the highway, 2002 4.3 Silverado (non-Vortec) lost power, died and would crank good but wouldn't start. Towed it home (where it's quiet enough to hear the fuel pump). Installed a new fuel filter (old one made noise when shaken) and still no start. Got 55+ psi fuel pressure. Pouring a little gas in the throttle body WILL make it start until that fuel is used up. Good spark, plugs, cap, rotor and wires. Engine analyzer didn't show any codes. 100,000+ miles, ran great until this happened. Any ideas????? SWAG's are welcome.

I'm still going with cam or crank sensor, or you have something un plugged somewhere.

:think:

If I remember right, 55psi is not enough to fire off the factory spider, needs to be between 60 and 62/63

Yep, just verified it, the poppet on the injectors won't open below 61psi. I bet your fuel pump is failing, even though you hear it prime it's not strong enough to build the needed pressure.

Nailed it.

The older CPI systems had common spider injector problems, but not the newer style as used on a 2002.

[bryanwheat]

http://www.theautoshop.net/VortecMPFI.htm They state 45 is what it takes to open them.

[snm95ls]

http://www.theautoshop.net/VortecMPFI.htm They state 45 is what it takes to open them.



I can tell you many personal experiences that 45 psi is not enough.

[Dman03GT]

http://www.theautoshop.net/VortecMPFI.htm They state 45 is what it takes to open them.

Once the engine is running, yes the newer system only requires 40psi to open the injectors.

"Fuel pressure in the CPI system with the key on and engine off (KOEO) should be about 58 to 62 psi. Some specs say 54 to 60 psi is OK, but some fuel injection experts insist that to start and run properly, most CPI systems really need at least 58 psi. Pressure is generated by a tank-mounted electric fuel pump. A fuel pressure regulator on top of the MAXI injector maintains operating pressure at about 55 to 57 psi when the engine is running."

I've worked with these fuel systems a lot, and if you're not around 60psi at key on, you're going to have issues unless you switch over to the electric injectors like they're selling in that link. Which are overpriced btw, I think you can buy them for less at O'Reilly as a walk in customer.

Here's a little more info as well...

"The first step in diagnosing a hard start or no start on a GMC or Chevy truck with one of these systems, therefore, would be to check fuel pressure. If fuel pressure is less than the KOEO specification, you need to test the fuel pump and its voltage supply circuit."

If the OP is @55 psi at key on as he suggested he IS below KOEO specifications. Granted he's off by only a few psi, but that's all it takes.

And if you still don't think that's right... the OP can pull the spider assembly out of the intake, hook the fuel lines back into the spider and crank his truck over. I bet it won't be spraying.

[bryanwheat]

OF coarse it isn't spraying, it has spark and won't start. I am not saying that pressure isn't the problem, just posting what an expert that build's custom fuel injector setup's has stated by posting the link.

[Dman03GT]

OF coarse it isn't spraying, it has spark and won't start. I am not saying that pressure isn't the problem, just posting what an expert that build's custom fuel injector setup's has stated by posting the link.

Hate to tell you, but if your expert is saying he only needs 45 psi at key on engine off to make the spider fire off he is dead wrong. While the vehicle is running though, the 45 is right.

And, that setup he is selling is not custom. Just sayin,
http://www.oreillyauto.com/site/c/detail/BWD0/63885.oap?ck=Search_02521_1384309_-1&pt=02521&ppt=C0024

[snm95ls]

Pressure differentials, how do they work.

:razz: