94 GMC 4.3 Sierra flooding out.

Rocyou · 09-21-2009, 10:19 PM

I have a Safari with a 4.3 , throttle body fuel injection.
Starts but will not rev up, too much gas.
I disconnected one of the 2 injectors and it will run, but very
little power, 40 mph tops.
Either injector works and either connector works the same.
There are no codes showing.
Anyone got any ideas? Thanks.

Rocyou · 09-21-2009, 10:47 PM

Sorry, that is a Safari, not a Sierra

**octaneman** · 09-23-2009, 06:40 AM

Hi Rocyou

Engine codes do not have to be set for an engine to run sluggish, a faulty mass air flow sensor or a TPS can present the same problem without any prior warning of the check engine light. The first step in determining the root cause is to perform a cylinder balance test. You will need to connect a fuel pressure tester to the fuel rail, and also an injector pulse tester to the injectors. Once the time in milliseconds is set on the pulse tester, turn on the key to pressurize the system (KOEO) then observe the gage's needle decent, this will clearly show if any injectors have a problem. Disconnecting any plugs or injector wires while the engine is running will not yield any positive results and can damage the ECU.

post back your findings.

**Midnight Tech** · 09-24-2009, 01:52 PM

How about the fuel pressure regulator?

titleist23chevy · 09-27-2009, 11:27 AM

It might be the EGR Valve that thing is very touchy it might seam that there is a flooding problem but it coould be sucking air after the EGR Valve or the EGR Valve is broke all together but just suggesting let me know

Rocyou · 09-30-2009, 05:30 PM

Hey, the injection is throttle body, and as I understand it, they are constant flow. Two
injectors. There is no fuel rail, so hooking up a pressure tester would entail piping in a connector. The regulator seems fine, but could the spring go weak, suddenly. This happened all at once.
Thanks for the heads up on disconnecting the injectors while engine running.

titleist23chevy · 10-01-2009, 01:44 PM

Hey man if its not that it migtht be the MAF sensor check the codes

Rocyou · 10-02-2009, 06:07 PM

there would be no MAF sensor since this is an older vehicle and has throttle body
fuel injection.

Rocyou · 10-02-2009, 06:13 PM

Mystery is solved.
The problem was a collapsed catalytic converter. Plugged the exhaust and
wouldn't let it run. Disconnected exhaust and it ran fine. Took converter off, cut off top,
cleaned out guts, and welded top back on. Works great.
Thanks everyone for the suggestions. Even tho we never came up with the solution here, it was helpful in getting the thinking process going and eliminating what was not wrong.

**Basementgeek** · 10-02-2009, 08:51 PM

I assume you know that gutting the converter is probably illegal.

BG

Rocyou · 10-03-2009, 08:51 AM

Illegal? whatever
But we do not have any pollution checks in Saskatchewan, Canada
With a Million people in a province the size of Texas, and neighbors so far away you can
only see them because the country is as flat as a board, I don't think it will make a lot of difference.
Grinding up pollution into tiny particles is a stupid solution anyway. It doesn't make them go away.

wolfen1086 · 10-03-2009, 04:11 PM

Here in Va, its illegal to gut a converter and it comes with Jail time, they check at inspections too, but I wouldn't gut one anyway because of the back pressure that some modern engines have to have to run properly, A GM product that year probably won't have any problems, but I'd put a new one one anyway cause Canada will become like the USA on inspections eventually

**Raylo** · 10-04-2009, 05:30 AM

Some of my f-body buddies did major mods to their motors (heads, cams, bigger injectors, 3" exhausts, dyno tunes, etc) and many of them removed the cats in the process. A good number of those have since reinstalled high flow cats due to the fumes coming into the cars while idling in traffic. The difference after driving clean cars for so long is startling. They also noted no decrease in performance. Other than cost there is no reason to remove cats. As for cost/benefit, it's a couple hundred $ vs. putting out the emissions of several hundred cars that have functional converters.

**Midnight Tech** · 10-05-2009, 10:08 AM

Actually you just fixed a symptom...it's getting too much fuel due to either a bad/misadjusted TPS, a faulty coolant temp sensor, or a bad ECM. All of these may not set a code.

09-21-2009, 10:19 PM	#1 (permalink)
Rocyou Registered User Join Date: Sep 2009 Posts: 6 OS: windows xp	94 GMC 4.3 Safari flooding out. I have a Safari with a 4.3 , throttle body fuel injection. Starts but will not rev up, too much gas. I disconnected one of the 2 injectors and it will run, but very little power, 40 mph tops. Either injector works and either connector works the same. There are no codes showing. Anyone got any ideas? Thanks. Last edited by Rocyou; 09-21-2009 at 10:49 PM. Reason: safari not sierra

09-21-2009, 10:47 PM	#2 (permalink)
Rocyou Registered User Join Date: Sep 2009 Posts: 6 OS: windows xp	Re: 94 GMC 4.3 Safari flooding out. Sorry, that is a Safari, not a Sierra

09-23-2009, 06:40 AM	#3 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 557 OS: WINXP	Re: 94 GMC 4.3 Sierra flooding out. Hi Rocyou Engine codes do not have to be set for an engine to run sluggish, a faulty mass air flow sensor or a TPS can present the same problem without any prior warning of the check engine light. The first step in determining the root cause is to perform a cylinder balance test. You will need to connect a fuel pressure tester to the fuel rail, and also an injector pulse tester to the injectors. Once the time in milliseconds is set on the pulse tester, turn on the key to pressurize the system (KOEO) then observe the gage's needle decent, this will clearly show if any injectors have a problem. Disconnecting any plugs or injector wires while the engine is running will not yield any positive results and can damage the ECU. post back your findings.

09-24-2009, 01:52 PM	#4 (permalink)
Midnight Tech Admin/Head GreaseMonkey/Igor's alter ego/Grand Exalted PoohBah Join Date: Dec 2001 Location: SC Posts: 2,924 OS: Windows XP Home/Pro SP3/Windows 98SE/Fedora Core 6/RH 7.2 with Autopoint/TAMS II	Re: 94 GMC 4.3 Sierra flooding out. How about the fuel pressure regulator? __________________ Please post all questions in the appropriate forum. Questions sent by email or PM will not be answered. Sharing my life...with my Imzadi! Interested in Trek gaming? Check out the Dynaverse! Proud supporter of the Carolinas Aviation Museum. If we have helped you in any way, please donate to keep TSF up and running!

09-27-2009, 11:27 AM	#5 (permalink)
titleist23chevy Registered User Join Date: Sep 2009 Posts: 3 OS: Windows Vista	Re: 94 GMC 4.3 Sierra flooding out. It might be the EGR Valve that thing is very touchy it might seam that there is a flooding problem but it coould be sucking air after the EGR Valve or the EGR Valve is broke all together but just suggesting let me know

09-30-2009, 05:30 PM	#6 (permalink)
Rocyou Registered User Join Date: Sep 2009 Posts: 6 OS: windows xp	Re: 94 GMC 4.3 Sierra flooding out. Hey, the injection is throttle body, and as I understand it, they are constant flow. Two injectors. There is no fuel rail, so hooking up a pressure tester would entail piping in a connector. The regulator seems fine, but could the spring go weak, suddenly. This happened all at once. Thanks for the heads up on disconnecting the injectors while engine running. Last edited by Rocyou; 09-30-2009 at 05:32 PM.

10-01-2009, 01:44 PM	#7 (permalink)
titleist23chevy Registered User Join Date: Sep 2009 Posts: 3 OS: Windows Vista	Re: 94 GMC 4.3 Sierra flooding out. Hey man if its not that it migtht be the MAF sensor check the codes

10-02-2009, 06:07 PM	#8 (permalink)
Rocyou Registered User Join Date: Sep 2009 Posts: 6 OS: windows xp	Re: 94 GMC 4.3 Sierra flooding out. there would be no MAF sensor since this is an older vehicle and has throttle body fuel injection.

10-02-2009, 06:13 PM	#9 (permalink)
Rocyou Registered User Join Date: Sep 2009 Posts: 6 OS: windows xp	Re: 94 GMC 4.3 Sierra flooding out. Mystery is solved. The problem was a collapsed catalytic converter. Plugged the exhaust and wouldn't let it run. Disconnected exhaust and it ran fine. Took converter off, cut off top, cleaned out guts, and welded top back on. Works great. Thanks everyone for the suggestions. Even tho we never came up with the solution here, it was helpful in getting the thinking process going and eliminating what was not wrong.

10-02-2009, 08:51 PM	#10 (permalink)
Basementgeek Moderator, Home Support Join Date: Feb 2005 Location: Central Ohio, USA Posts: 1,518 OS: XP Pro SP2/Vista Ultimate SP2 Blog Entries: 3	Re: 94 GMC 4.3 Sierra flooding out. I assume you know that gutting the converter is probably illegal. BG __________________ Donating to the forum keeps TSF free for all. Proud member of ASAP

10-03-2009, 08:51 AM	#11 (permalink)
Rocyou Registered User Join Date: Sep 2009 Posts: 6 OS: windows xp	Re: 94 GMC 4.3 Sierra flooding out. Illegal? whatever But we do not have any pollution checks in Saskatchewan, Canada With a Million people in a province the size of Texas, and neighbors so far away you can only see them because the country is as flat as a board, I don't think it will make a lot of difference. Grinding up pollution into tiny particles is a stupid solution anyway. It doesn't make them go away.

10-03-2009, 04:11 PM	#12 (permalink)
wolfen1086 Registered User Join Date: Oct 2007 Location: Va Beach Posts: 260 OS: Win XP SP3	Re: 94 GMC 4.3 Sierra flooding out. Here in Va, its illegal to gut a converter and it comes with Jail time, they check at inspections too, but I wouldn't gut one anyway because of the back pressure that some modern engines have to have to run properly, A GM product that year probably won't have any problems, but I'd put a new one one anyway cause Canada will become like the USA on inspections eventually __________________ I'm gonna rot ? yea I know, might as well smile in the mean time :)

10-04-2009, 05:30 AM	#13 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: 94 GMC 4.3 Sierra flooding out. Some of my f-body buddies did major mods to their motors (heads, cams, bigger injectors, 3" exhausts, dyno tunes, etc) and many of them removed the cats in the process. A good number of those have since reinstalled high flow cats due to the fumes coming into the cars while idling in traffic. The difference after driving clean cars for so long is startling. They also noted no decrease in performance. Other than cost there is no reason to remove cats. As for cost/benefit, it's a couple hundred $ vs. putting out the emissions of several hundred cars that have functional converters.

10-05-2009, 10:08 AM	#14 (permalink)
Midnight Tech Admin/Head GreaseMonkey/Igor's alter ego/Grand Exalted PoohBah Join Date: Dec 2001 Location: SC Posts: 2,924 OS: Windows XP Home/Pro SP3/Windows 98SE/Fedora Core 6/RH 7.2 with Autopoint/TAMS II	Re: 94 GMC 4.3 Sierra flooding out. Actually you just fixed a symptom...it's getting too much fuel due to either a bad/misadjusted TPS, a faulty coolant temp sensor, or a bad ECM. All of these may not set a code. __________________ Please post all questions in the appropriate forum. Questions sent by email or PM will not be answered. Sharing my life...with my Imzadi! Interested in Trek gaming? Check out the Dynaverse! Proud supporter of the Carolinas Aviation Museum. If we have helped you in any way, please donate to keep TSF up and running!