Author Topic: So it isnt my fuel pump **TROUBLE CODES ADDED 4/19** *VIDEO ADDED 4/16*  (Read 28581 times)

Offline 87ChevyR10

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After being stuck with repeatedly replacing airtex fuel pumps thru exchange after exchange, friday my truck went out again with the same symptoms as it has everytime an airtex fuel pump has gone out on me. Pulled up to the gate of the neighborhood, truck sputtered, cut off, could hear the fuel pump on at one point, off another. So i limped it in, parked it. FF to today, i replaced the fuel pump and strainer with an AC Delco, no prob on the install. Crank it up, still rough idle/sputtering. Its driveable in terms of the definition of the word, but not driveable for the street with it acting that way.

What is going on here fellas? Fuel filter perhaps? I havent replaced that yet thru the last 3 pump switches, maybe so?

oil is F/S with less than 3000 miles, new plugs, new wires. I put lucas injector thru religously every 5 tanks or so.


Help.......  :(



« Last Edit: April 19, 2013, 04:47:56 PM by 87ChevyR10 »

Offline Tx Firefighter

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So it isnt my fuel pump
« Reply #1 on: April 10, 2013, 06:15:22 PM »
Put a new filter on it. The thing is likely clogged up and killing your pumps.

Always replace the filter when doing a fuel pump.

Offline VileZambonie

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Re: So it isnt my fuel pump
« Reply #2 on: April 10, 2013, 08:03:24 PM »
What makes you think it's the fuel pump?

Start from the beginning - Any codes? Did you ever verify your fuel pressure? Have you tuned it up? When it dies have you verified injector pulse and spark?
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Offline 87ChevyR10

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Re: So it isnt my fuel pump
« Reply #3 on: April 16, 2013, 01:45:26 PM »
What makes you think it's the fuel pump?

Start from the beginning - Any codes? Did you ever verify your fuel pressure? Have you tuned it up? When it dies have you verified injector pulse and spark?

I've replaced 3 airtex pumps in less than a year after having another brand in it for years.

Nah, no codes, no obd1scanner, but ive ordered one from autozone. Haven't verified fuel pressure/pulse/spark, no tools to do so. I've done aight to replace the fuel filter and pump myselfso far. I've called a mobile mech. out here and came up with nothing. He ohm tested the map sensor circuit, said it wasnt giving a reading, so i went and replaced that, no good. Bought a haynes and a chilton, just frustrated right now. I'm kinda stuck until i get the obd1 in hand to pull the codes. Theres a fuse i could check to see if its blown that deals with the injectors/fuel system right?

Put a new filter on it. The thing is likely clogged up and killing your pumps.

Always replace the filter when doing a fuel pump.
Done. Replaced with a fram. Still no green light.


Offline 87ChevyR10

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Re: So it isnt my fuel pump
« Reply #4 on: April 16, 2013, 03:16:02 PM »


heres a video with audio of the rough idle/drop off.


Offline VileZambonie

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #5 on: April 16, 2013, 08:37:36 PM »
You don't need a code reader to pull codes all you need is a paper clip. Jump the A&B terminal in the data link connector and turn the ignition switch on. It should flash codes at you starting with 12. flash pause flash flash is code 12 and so on. Did you check for vacuum leaks at the base of the throttle body? Is the vacuum hose connected to the TBI unit and to the MAP sensor?
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Offline 87ChevyR10

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #6 on: April 16, 2013, 10:26:07 PM »
You don't need a code reader to pull codes all you need is a paper clip. Jump the A&B terminal in the data link connector and turn the ignition switch on. It should flash codes at you starting with 12. flash pause flash flash is code 12 and so on. Did you check for vacuum leaks at the base of the throttle body? Is the vacuum hose connected to the TBI unit and to the MAP sensor?

Ive read bout the paper clip method but im not really one for automotive morse code. on the vacuum leak, havent checked that, and yes, the hose is connected. I doublechecked after replacing the map sensor

Offline 87ChevyR10

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #7 on: April 16, 2013, 10:27:09 PM »
Vile - u check the video?

Offline VileZambonie

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #8 on: April 17, 2013, 07:35:01 AM »
Spray some carb clean at the base of the throttle body with it running and see if it changes engine speed.
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Offline Fairlane514

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #9 on: April 17, 2013, 04:05:58 PM »
Hook up a vacuum gauge to full manifold vacuum source and see what it tells you.

Offline Twin_Turbo

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #10 on: April 17, 2013, 05:26:57 PM »
the surging idle is the IAC opening to prevent it from stalling out.   How is the spray pattern? constant or is it increasing and decreasing the pulses (as in, non continuous stream of fuel)? 

There's some stuff you can check. If you have a FP gauge check for a constant pressure.  How did you hook the pump to the hard line on the level sender? rubber FI hose? Hose clamps or not? I always prefer to clamp them down for a leak free connection. Also, if you reused the old coupler section did you check for cracks/splits?

Check the MAP hose, if it's a very soft hose, vac can collapse it and the map sensor will pick this up giving a suring idle


another reason could be too rich fueling because of a bad CTS, flooding the engine and the IAC violently opening it to keep it from stalling and then settling back to a normal idle position.

Having an actual diagnostics tool like a snap on red brick is a big help in determining what's going on.

Offline 87ChevyR10

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Re: So it isnt my fuel pump *VIDEO ADDED 4/16*
« Reply #11 on: April 19, 2013, 04:17:15 PM »
Ok, everything came this morning so i pulled the codes and after reviewing, man, could this be something as little as a blown fuse problem? Thru the code results, it looks like everything relating to the fuel system is having an issue, low or high voltage or both. Maybe? check the codes.... 33/34 cant be because i just replaced that map sensor, so thats strange.

Code 13 - Oxygen Sensor Circuit
signal stays low ("lean") during warm engine cruise or sensor is open, or left circuit sensor is open(for dual sensor models)

Code 22 - Open Throttle Position Sensor Circuit
signal voltage is low during engine idle OR fuel cutoff relay circuit - opened or shortened to ground

Code 32 - Exhaust Gas Recirculation System
BARO sensor bad OR EGR valve diag. switch - closed during engine startup  /  or open when EGR flow requested by ECM

Code 33 - Manifold Absolute Pressure/Mass Air Flow Sensor Malfunction
signal voltage is high during engine idle (engine misfire or unstable idle may cause this code)

Code 34  - Manifold Absolute Pressure Sensor Malfunction
signal voltage is low when ignition on

Code 43 - Electronic Spark Timing Malfunction
ESC (Electronic Spark Control) circuit problems / EST (Electric Spark Timing) circuit is low voltage detected

Offline Irish_Alley

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Re: So it isnt my fuel pump **TROUBLE CODES ADDED 4/19** *VIDEO ADDED 4/16*
« Reply #12 on: April 20, 2013, 07:12:44 AM »
what i would do. is reset the ecm drive it for a bit till the cel comes back on then test the codes again see which ones are still there. will all them code i would almost think the ecm is the problem but idk never really worked on a 87. but reset the codes and see what you get cause you never know which codes are recent or old
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Offline VileZambonie

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Re: So it isnt my fuel pump **TROUBLE CODES ADDED 4/19** *VIDEO ADDED 4/16*
« Reply #13 on: April 20, 2013, 05:11:26 PM »
Those codes were most likely set by someone plugging in and unplugging sensors. Did you spray carb clean at the base of the tbi yet? Unhook the vacuum hose at the EGR valve after you check that as well and see if it runs any different.
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Offline 87ChevyR10

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Re: So it isnt my fuel pump **TROUBLE CODES ADDED 4/19** *VIDEO ADDED 4/16*
« Reply #14 on: April 20, 2013, 06:00:36 PM »
Those codes were most likely set by someone plugging in and unplugging sensors. Did you spray carb clean at the base of the tbi yet? Unhook the vacuum hose at the EGR valve after you check that as well and see if it runs any different.

Vile -
Well, i sprayed the intake/injectors out with carb cleaner,which actually made the idle smooth now. This morning reset the ecm by unplugging the two ecm fuses and turning the ign off and back on. Also unplugged the battery after. No change, til the carb cleaner. I also sprayed carb clean around all the vacuum hose connections, the intake, no change in idle/revving. So a vacuum leak it doesn't appear to be.

So i am left with 2 major possible options(bad fuel pump relay/EGR seized up) and another option lingering on the outskirts(IAC).

I spoke to my dad just now, he said more than likely, if i cant reach up in the egr valve and move it, it seized up with carbon deposits, rather "BS" as he termed it. lol. But he said he'd replaced the relay already which i didnt know of. He was pretty adamant it wasnt the relay.

Should i try to see what codes come up now? I feel like im close, considering the improvement in the idle, but i tried driving it around the neighborhood on a test run and that was a no go. Heavy boggin down/hesitation when it come to accelerating.

I just wanna say thanks to everyone taking the time to help and post, this ones got me thrown for a loop.

If i need a multimeter for anything to test, lmk cause i just dropped 30 on one. So im in the game there now.