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1998 Suburban vortec 454 / 7.4 Drivability Issue

David Masch

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David Masch New Member

David Masch

Posted
Posted

I typically work on diesels so bare with me.. THanks

I'm working on a 98 Suburban seems to idle OK but smells a bit rich.

Fuel pressure with Key On hits 60PSI then drops to 55. 

At Idle floats around 50 and drops 2 PSI when rev'd up to 3500rpms or so, shouldn't it rise??

When I Rap the throttle the pressure will jump to 60ish then back down.

Problem 1 - Bad Fuel Regulator, I presume

When I unplug the Mass Air Flow Sensor while idling she dies??

leaving unplugged she will start and seems to run and respond better to throttle rap.

Problem 2 -Bad MAF Sensor.

Was also informed that the shop that worked on it before said 1 injector or to rich, BUT when I connect my laptop Autoenginuity does not give any PID information except O2 sensor data, Not fuel trims etc, they said that might be all PCM reports on that year..??.. I do have the GM enhanced modules.

 

SO the biggest issue is; when driving and the throttle is punched she misses like crazy no power.

BTW, it recently has had installed; New fuel pump, filter, plugs and wires.

 

I'm thinking I need to install; Injectors, regulator, MAF

 

Thought's?

 

Thanks in advance

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