Question about 1991 Isuzu Impulse

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1989 GMC 2500 5.7L - engine surges and stalls at idle. Loses power at cruising speed. I've already changed, plugs, cap, rotor, wires, fuel pump,filter & lines, TPS, IAC, EGR, MAPP Sensor, intake gaskets, checked vacuum lines, replaced distributor, catalytic convertors, Throttle body gasket and cleaned injectors. HELP - We are at a loss!

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Wow you have replaced a lot of stuff. Lets go back to the Fuel pump. When you replaced it did you replace the hose between the pump and the sending unit. These are common for splitting. Have you hooked up a fuel pressure gauge to check what pressure you have? It should be real close to 13 psi and should raise to at least 18 or 19 when you pinch off the return line.

Posted on Jun 02, 2009


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1989 ford stalls when idling ,runs rough at idle

Check for any trouble codes in the engine computer, and have the fuel pressure tested. If it is throttle body injection. observe the spray pattern of the injector when it pulses. You should see a cone pattern of the fuel spraying down into the intake. If it drips, or appears anemic, the injector might be partially clogged. Try some injector cleaner in the gas tank.

Mar 03, 2012 | 1989 Ford Tempo

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Remove the vacuum lines on the bottom front of the throttle body with the engine off. Check each hose connection with a nail; small screwdriver or a small drill bit. Make sure they are not clogged. If they are clean them out carefully. If they are not clogged, then check to make sure the vacuum lines aren't obstructed. I refer to your idling up and down as hunting. Reconnect the vacuum lines and start the engine. If it idles smoothly, your found your problem. Good luck.

Sep 13, 2011 | GMC C1500 Cars & Trucks

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Have a 1989 gmc 1/2ton that surges at aprox.50 to 60 kmh changed fuel pump and fliter no change cap and rotor are good spark plugs aer new wires are a year old

Surges are not exactly fuel related so stop spending that money. Have a diagnostic done. Surges are pc related. Faulty info in most cases.

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Missfiring while cruising

might want a valve regrind and new valve springs??But most likely cause is the the ecu wants resetting because the fault you describe is similar to when the dwell angle was wrong ,early citreons and peugots with the first electronic systems were like this ,it was done to give max fuel consumption which it did with over 50miles per gallon but ??? they did seem to give the same ride you describe

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Idling Problems

Note that all cars don't have the same symptoms as stated in the following procedure to cure your problem.
Here are the most common causes of surges, stalls at stops, low erratic idle speed, rough idle and engine hesitation, it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Mar 31, 2009 | 1989 Volkswagen Cabriolet

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