dakota's rx7

iTrader: (9)

ok i have an 86 N/A i think it has bad fuel pressure. it should be 64 to 85 and im only getting like 60. so do i just need a new fuel pump. if so does any one i could have for a cheap price?

Rx7_Nut13B

iTrader: (1)

Fuel pressure should only be about 32-45psi in the fuel rails, are you dead heading the pump to get thows pressures?

dakota's rx7

iTrader: (9)

no i crank the car over and i was jus testing it right after the fuel pump it was reading 60 psi. the car would run for like 3 seconds then fall on its face if you would try to give it gas it would fall on its face faster.

RotaryRocket88

iTrader: (7)

Again, did you have a gauge tee'd into the feed line to the engine (after the fuel pump), or was the gauge just stuck in the end of the line with nowhere for fuel to go? The second is dead heading, and is what the 64-85 psi spec is for.

Try jumping the yellow fuel pump test connector on the passenger shock tower. Start the car and see how it reacts. If there's a difference, there could be a problem with the fuel pump switch in the AFM.

dakota's rx7

iTrader: (9)

it was not jus hooked to the fuel pump it was hooked up right after the fuel filter in the engine bay no dead heading. and what do you mean jump the wire like hook a batter charger to the yellow wire and then try to start the car and see if it runs. because the car falls on it face real hard when i go to give it gas and starts to pop. ok thanks for all your guys help i appricate it.

klint

He's talking about runing a little wire into each socket on the yellow electrical plug in , inbetween the airbox and the passenger shock tower it's usually right below the stock boost sensor, grab the socket (it won't be plugged into anything) and take a short peice of wire and loop it into each plug on the outlet to make a conection between them, then try to start the car and see how it runs , this plug eliminates the sensors that affect your fuel pump, if it runs good then it could be your afm or your fcs, anyway hope you understand good luck

Rx7_Nut13B

iTrader: (1)

OOOO Check this out,

You can start it right?
It will idle Right?
But when you touch the gas it will die?

While it is idling push in on the MAF flapper door, like the motor is pulling in more air, if it dies then it isnt the MAF if it doesnt change at all then it is the MAF or the wiring to the ECU from it.

I had one do the same thing, and it was the wiring.

RotaryRocket88

iTrader: (7)

Stock fuel pressure at idle should only be about 28-32 psi. If you had a gauge tee'd in after the fuel filter, there's no way you should see 60 psi there. The NA fuel pump can't even operate in that pressure range. It would take ~75 psi at the pump to produce 60 psi at the rail, and the NA pump flows about 0 LPH at that pressure.

So first, does the car idle? Or does the problem only come up when you try to accelerate? I'd start by see what the fuel pump connector does, then test the AFM, pressure sensor and TPS. The FSM has resistance/voltage tests for each. A dead spot in the range of the AFM door or TPS could cause acceleration related problems.

dakota's rx7

iTrader: (9)

ok now i know what your talking bout with the wire thing. and it runs for but 3 seconds then dies but in that 3 second if you step on the gas it jus falls faster and i will test everything this morning and let you guys know how it is. and i will try to post some pics of the car pressure at 60 psi. maybe it isnt stock idk i got the car for a paintball guns so ya i dont know much bout them but trying to learn thanks for all your guys help agian.

RotaryRocket88

iTrader: (7)

My guess would be a bad AFM fuel pump switch. When the flapper door is open on the AFM (engine running & pulling in air), it's supposed to allow the circuit opening relay to supply power to the fuel pump. The FSM has a resistance test for this function.

Go ahead and jump the fuel pump connector. If it runs with it connected, it's the AFM switch. If it still dies, you can rule it out.

A second suspect would be the fuel pump resistor/relay. I've heard of similar problems caused by a bad one. You can find pictures and tests for it in the FSM, as well.

dakota's rx7

iTrader: (9)

well i bridge that wire a few days ago and it ran for 15 seconds instead of 6 seconds so there was a slight inprovment but i still yet to try some of the other test so im going to do that. if its a bad afm fuel pump switch were would that be located at so i could track it down and get it fixed.

RotaryRocket88

iTrader: (7)

The switch is part of the AFM itself. Replacing it would mean replacing the whole thing. I'm sure you could find a used one for cheap, but you should test it with a multimeter as per the FSM first.

dakota's rx7

iTrader: (9)

how many ohms so the afm in the book it doesnt tell me

RotaryRocket88

iTrader: (7)

FSM page 4A-54 gives you all the values. Resistance between E1 & Fc will be infinity with the door closed (fuel pump off), and 0 with the door open at all (fuel pump on).

http://www.rotaryheads.com/PDF/2nd_g...systems_na.pdf

dakota's rx7

iTrader: (9)

thanks for all the help i did all the test and it came down to a bad afm i switch it out with the other afm i had and now it runs great. but theres a new proublem that jus accured. the flex tubing that is used for a down pipe turned cherry red and the muffler were only a little warm so i got plug mufflers i think. could there be anything else pluged

RotaryRocket88

iTrader: (7)

Plugged cats are more likely.

dakota's rx7

iTrader: (9)

dont have cats. they were cut off and put straight tubing all the way back

klint

There should be two cats one one the downpipe and one on the mid section of exhaust some people just bang out the top cat and keep the downpipe on and replace the mid cat with a straight pipe, if there is a wider section on the downpipe take it off and make sure there's no cat if so just bang it out. thats not good for the pipes to heat up like that . while the downpipe is off check you exhaust part of your turbine make sure theres no damage and it spins easily, any way good look

dakota's rx7

iTrader: (9)

thers no cats on the car. i checked and i seen that theres like a flex tubing thing for like a down pipe then its straight pipe all the way back