GSI 5.7 TBI fuel injectors? you can feel the Burt’s in

Shaper79

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So if I’m at 4200 rpms at WOT 17 pitch and I slightly pull back on the throttle and stab it again in a rapid motion. I can build up to 4600 rpms with each rapid back and fourth bump I can feel the burst of Speed and HP. It slowly backs its self back down to 4200rpms. Yes I have checked to see and set linkage to make sure Throttle is all the way open. Anyone else experience this. I have new fuel pumps. And cleaned paint chips out of carter fuel cell. New screens on fuel injectors, all new ignition system even new OEM ignition module. The only thing I can think of now. Is getting new TBI fuel injectors. But I can’t seem to find a part# for them.
 

alldodge

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Merc injectors for the same motor and year are still available 852956A1 , and if you search on it you will also find a VP number of 3858941

That's the best I can come up with
 

Shaper79

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Oh. Nice thank you that will work. Alldodge does this sound like an injector’s problem to you.
 

alldodge

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No I'm thinking fuel pressure is falling off. You back off, pump fills everything then go again and pressure starts bleeding down. Injectors are electrical, so they either work or they don't. While they might get warm and start having issues, but letting off for a sec and back on should not make them come back and work correctly

Fuel supply is my first guess. Pressure issue due to tank vent, restriction, pump or maybe the regulator
 

Shaper79

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Ok. Thanks. I’ll check the pumps again. I found out the injectors are the same as the 94-95 gmc 7.4l. If the pumps check out good. Could it be I need to up the psi on the fuel pressure regulator. I did the TBi rebuild kit last year. And the stock spring was the 12 psi spring. And just ordered new pumps from mancave mechanic and the O-Ring kit. And cleaned all the paint chips out of the carter fuel cell. The ant syphon valve is good. I easily suck fuel from the tank. I don’t know were the tank vent is. I’m just down to either. I need new injectors. Or up the fuel pressure regulator spring
 
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Shaper79

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Naw. Did another fuel pressure test on the HP pump. 28psi at idle. If I take it up to 2000 rpms stays at 25psi. Took the pump out and sure enough more paint chips. The low pump is a solid 8 psi. So I’m going to buy some paint remover an pull the cell apart and poor it into the float bowl. Let it sit. Then pressure wash the **** out of it. This is the second time to clean those damn paint chips. Can’t believe Volvo would do something so stupid!!
 

Lubak572

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My pumps were recently replaced. Did VP fix this issue on the new pumps or are they still painted?
 

Shaper79

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It’s the bottom of the float bowl that is painted. I took mine apart last weekend and cleaned out every fking spec of paint. Now I need to go check the ant syphon valve.
 

Walt T

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By the way the TBI injectors can be had at your local auto parts store. They have numbers on them and can be cross referenced easily. You'll need a good parts person though not some young kid who is helpless without a computer and wants a year make and model of a car. Way cheaper than Merc or Volvo
 

Shaper79

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Yes. I got them cross referenced for flow rate. They are 94-95 7.4 liter gm injectors
 

Shaper79

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Close thread. Problem solved. Fuel regulator needed more psi from set screw.
 
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