2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

could fuel pump cause hesitation?

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Old 03-04-09 | 04:15 PM
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EmbassyBlack's Avatar
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From: Windsor ontario
Unhappy could fuel pump cause hesitation?

Ok so i'm pretty sure i'v tried almost everything to figure this damn problem out but it still wont work right. I don't like starting new threads about this but i really need some more opinions on the subject. Every thread that iv read so far hasn't really helped me out. The problem is i cant rev past 4k. Heres a list of what iv tried so far.

4 different ECUs
2 boost sensors
grounded pin 2c on the ECU
cleaned/ re-grounded the boost sensor, the ground on top of the engine, and the battery ground.
Tried a few sets of injectors
4 tps sensors
New fuel filter
New plugs
Tested the solenoid resistor box (not sure if the dmm was on the right setting so heres a pic) . On that setting it showed 5.8 ohms, under all the other ones it was 0.
The secondaries have 13ish volts to each of them, i also ran a new wire from the injectors to their wire right before the connection to the Solenoid resistor.
Iv done most of what it says to do in the factory service manual.
The only mod i have is i replaced the cats with a 2.5 pipe up to the Y.

The only other thing i can think of is maybe the fuel pump or strainer might be dirty. If you guys could give me some advice, something i havn't tired yet id really appricite it. Im gunna check the fuel pump tomorrow. But other than that im all out of ideas.
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Old 03-04-09 | 04:24 PM
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HAILERS
 
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From: FORT WORTH, TEXAS,USA
Well? Pull the pressure line off the fuel pump and install a fuel pressure gauge on the hard line of the pump. Turn the key to ON and jumper the fuel pump check connector. The pressure output of the pump should what's written in the FSM. Something on the order of 80PSI or so. See book.

IF it's good there, then put that stuff back together and then pull the pressure line off the engine and install a pressure gauge on the line coming out of the filter. Same deal, key On etc. The pressure should match what you see in the FSM and should read the same as what you read at the pump.

Then install the fuel pressure gauge in a Tee b/t the line out of the fuel filter and the hard line on the engine. Idle the engine. Should read approx 30psi give or take a couple. Then turn the engine off, key ON, and jumper the fuel pump check connector. The reading should be approx 39psi.

So, yes. Check out the fuel pumps pressure.
Old 03-04-09 | 05:19 PM
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ok so im trying to take my fuel pump out right now but everything is rusted. i checked the fuel pressure and its only 60psi at the hard line, so im guessing thats deff the problem

buttt all the screws are rusted over, any suggestions on how im gunna get that damn thing out?
Old 03-06-09 | 07:54 AM
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From: FORT WORTH, TEXAS,USA
Just get a drill motor and a drill bit that is just a little smaller than the diameter of the head itself. Drill the heads off. Just the heads. The heads should fall off or spin off leaving the shank.

Remove the pump.

Then unscrew the shank of the screws with your fingers. Buy new screws??? where? size? got me.

Your meter was on diode check. Move it anti clockwise to the next figure, the 200 ohm figure. The plug on the solenoid resistor.....the middle pin feeds power thru the the resistors to the other pins. So one meter lead on the middle pin and then the other lead to the other pins one at a time. Approx 6ohms (written on the side of the individual resistors in the package) give or take a tash.

Put a new fuel pump filter on your old pump and try the psi check again. Make sure your battery is up to snuff.

The series four turbo pump is supposed to put out 71-94 psi.

The series four non turbo is supposed to put out 64 to 85.3 psi.

So if yours was a series four non turbo, you'd be close to the low figure. The state of the battery will make some difference. How much? Makes on wonder if you read 60psi that "what would happen if you jumpered another car to that battery to keep the voltage up (other car idling or higher) ..then would the psi go up a few psi???? Faster the pump turns means more output.

Ever check your alternators output using a meter AT the alternator? Positive lead on the large B terminal and the negative lead on the case of the alternator. DC volts. Should be over 14vdc. Mabe rev it up to 2 grand to check the total output.
Old 03-06-09 | 12:51 PM
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HAILERS
 
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From: FORT WORTH, TEXAS,USA
I did that jumpering another car to the one being tested for fuel pressure AT the pump. It rose the pressure 4psi over just using the tested cars battery. I'd want more than the minimum pressure of 64psi.

Actually my series four non turbo is on the low side. Just the wrong side of the low side figure. Sucks. Need pump. It's not showing any hesitation symptoms though.
Old 03-06-09 | 07:43 PM
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From: Windsor ontario
Nope, not fuel fuel problem. Everything is good in that department. Hailers you've been very helpfull thanks. But its still not fixed so im really lost now lol
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