Fuel Pump Question
Thread Starter
Racer
Joined: Jan 2010
Posts: 347
Likes: 12
From: Deltona FL
Fuel Pump Question
I have been researching my hesitation bogging problem and I have read that some found the problem to be a bad fuel pump under a load.
I thought that a fuel pump put out a constant volume whether at idle or higher rpms, The pump states 40 gph is this varible based on rpm? if it is a steady output would'nt the problem been a regulator or a filter and not the pump or am I missing something?
I thought that a fuel pump put out a constant volume whether at idle or higher rpms, The pump states 40 gph is this varible based on rpm? if it is a steady output would'nt the problem been a regulator or a filter and not the pump or am I missing something?
Team Owner
Joined: Jan 2003
Posts: 20,297
Likes: 240
From: Summerland B.C. Canada
Yes, if the pump is failing and only turning half the normal rpm, it will supply enough fuel to satisfy low demand and allow reg to return some back to tank.
Increase demand, now the pump can't supply enough fuel to keep the pressure at the required level, motor starves until load is reduced.
A bad fuel filter can cause the same problem. A pressure gauge, taped to windshield, is the best way to see what's happening, when demand is increased.
Increase demand, now the pump can't supply enough fuel to keep the pressure at the required level, motor starves until load is reduced.
A bad fuel filter can cause the same problem. A pressure gauge, taped to windshield, is the best way to see what's happening, when demand is increased.
Drifting
Joined: Sep 2002
Posts: 1,642
Likes: 0
From: Suwanee,Ga
From the FSM '89 model here's a dozen.
#1 Fuel Pressure
#2 Bad fuel
#3 Air leaks at MAF/Throttle body
#4 Plugs
#5 MEM cal... I don't think so
#6 TPS sticking or binding voltage should increase when throttle opens
#7 Timing
#8 Alternator hay wire less than 6v more than 16v
#9 Dist gnd
#10 Emission canister sys
#11 EGR
#12 Bad Inj.
TJM
#1 Fuel Pressure
#2 Bad fuel
#3 Air leaks at MAF/Throttle body
#4 Plugs
#5 MEM cal... I don't think so
#6 TPS sticking or binding voltage should increase when throttle opens
#7 Timing
#8 Alternator hay wire less than 6v more than 16v
#9 Dist gnd
#10 Emission canister sys
#11 EGR
#12 Bad Inj.
TJM
Team Owner
Joined: Jan 2009
Posts: 73,568
Likes: 33
From: Somewhere in Mo
St. Jude Donor '09-'10, '14
I was going to start a thread in regards to the fuel pump pulsator but I thought I might ask my question here. Don't mean to do a DB Cooper (hijack) my advance apologies.
Maybe Agent 99 can answer my question.
I have a fuel delivery issue. My 90 starts and then immediately dies. If I give it gas it will run fine but it won't idle. I have narrowed it down to the fuel pump, or the pulsator, or possibly the regulator. although I don't feel it's the reg as the reg passes preliminary trouble shooting.
I'm thinking it is the pulsator. So if I want to replace the pulsator with a hose, what size hose do I need? Anyone know off the top of their head?
I ordered a complete Racetronix fuel pump and kit fro Thunder Racing, but I am tired of waiting on it, I ordered it on 12/21/09 and everytime I call them they tell me in a couple days. I'm tired of their BS.
Maybe Agent 99 can answer my question.
I have a fuel delivery issue. My 90 starts and then immediately dies. If I give it gas it will run fine but it won't idle. I have narrowed it down to the fuel pump, or the pulsator, or possibly the regulator. although I don't feel it's the reg as the reg passes preliminary trouble shooting.
I'm thinking it is the pulsator. So if I want to replace the pulsator with a hose, what size hose do I need? Anyone know off the top of their head?
I ordered a complete Racetronix fuel pump and kit fro Thunder Racing, but I am tired of waiting on it, I ordered it on 12/21/09 and everytime I call them they tell me in a couple days. I'm tired of their BS.
Last edited by RetiredSFC 97; Jan 23, 2010 at 10:31 AM.
