jumping the fuel pump resistor

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

montanacruiser

montanacruiser

10 Year
Joined
Sep 28, 2012
Threads
63
Messages
247
Location
Missoula MT
Hi all having some problems with my truck. I went to start it this morning and the truck fires then dies right away. I read a little looks like it may be a bad fuel pump resistor. I see that you can bypass it or jump it some how. How would I go about that?
Thanks
 
Unplug connector and jump the wires. You could cut them and twist them together. If you wanted to go really hill billy you could jam copper wire into each connector.

It's unlikely that the resistor is just magically killing your truck though. And there a whole host of other things I would check first - fusible links, I'd check voltages at connectors etc.
 
I agree, the resistor just slows the pump down so there's something else is amiss here. But, it's a quick check just to jump it out of the circuit.
 
Well I am still at a stand still. I bypassed the resistor with no affect. I checked continuity in my fuseable link and it looks good. I did end up ordering one because mine is looking rough. What connectors should I check the voltage? Any other ideas?
Thanks Again I really appreciate the help.
 
I would try bypassing the fuel pump relay. It's function is to switch in/out the resistor. Check the wire connections at the fuek pump itself and run a direct power connection to the pump to eliminate all the control circuits. The other possibility is the fuel cutoff circuit inside the VAF meter.
 
It sounds like the fuel pump is being *told* to stop running so we need to find out why. I've attached the EWD for the ECU (TMA - too many acronyms).

I wish I had the Adobe Acrobat so that I can break up the pages. Anywho, on pdf page #8, the "circuit opening relay (COR)" is responsible for the activating the Fuel pump relay (FPR). The COR is getting power from two different sources: Follow the B-L wire all the way to page #3 and you'll notice it is get fed by a 7.5a IGN fuse and the IGN switch. The other end of COR is getting fed by the R-W wire which is coming from ECU pin # 14, labeled "FC" terminal, on page 7.

copy/paste from page 2 of EWD:

FUEL PRESSURE CONTROL SYSTEM

The fule pressure up system causes the VSV (fuel pressure control) to come on for high temp, starts and immediately after starting in order to increase the fuel pressure, improve start ability at high temps and provide stable idling. The engine control module evaluates the signals from each sensor (input signal from (1), (2), (5), (11)), outputs current to terminal FPU and controls the VSV.

Fuel pump control system - the engine control module operation outputs to the terminal FPR and controls the fuel pump relay (FPR) and thus controls the fuel pump drive speed in response to conditions.
 

Attachments

Hi all

Montanacruiser, did you find the problem?
I have the same currently on my 105 4500EFI. Testing now with the resistor bridged out, as I only get a new one in a couple of days ex Japan.
Same symptons as opening post, but intermitant. Runs fine for a while then suddenly revs up and dies. Fuel pump pressure is perfect, on both pumps, main and sub.
 
anyone find a fix? i have a 2005 tundra limited and it cuts off right after start and in the beginning it would and still now if its cold it some times cut off coming to a stop just after leaving the drive way at the first or second stop sign
 
Evscholla said:
Bump
Click to expand...

cutting off at a stop sign can point to IAC valve, possibly. if the IAC is faulty, the engine idle goes to crap or it stalls. They just need to be cleaned often times because of a tiny orifice thing.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom