M35a2 FUEL QUESTION PLEASE HELP

[deucesarewild]

Just wanted someone to help with me with my thoughts of why truck wont stay running. I can fill fuel filters with diesel and prime the system and truck will run great until filters run out, then shuts off, stops getting fuel. Does this sound like bad fuel pump? These trucks are new to me, any suggetions or thinks to look for would be greatly appreciated. Thanks in advance.

 

[mdmorgan]

Yes.

 

[73m819]

check the fp fuse

 

[RedbeardTheZombieHunter]

Even if the lift pump in the tank is dead, the injection pump is usually strong enough to keep the truck running. Did you check the fuse under the cover on the pump access plate on top of the fuel tank? It's right where the power wire for the pump hooks up on the cover plate.
After that, inspect the fuel lines and make sure you don't have a crushed spot in any of the hard lines. After that, time to look at the injection pump. Good luck!
Oh BTW, I seem to remember something about the fuel line running around under the radiator. That would be a good place to check for a crushed spot too.
opcorn:

 

[Flyingvan911]

Or your fuel filters are clogged. Use the search box and you'll find lots of threads discussing fuel issues of all kinds.

 

[deucesarewild]

ok will do, the reason I wasnt sure is I have seen people claim their trucks have ran with bad fuel pump for long periods of time. Just wanted to make sure I'm starting in the right place. Also since it will run when primed means IP and fuel booster on IP are good?...Thanks again I'm defininetly a newbie.

 

[Flyingvan911]

Read through the deuce forum. There are volumes of info. Welcome to Steel Soldiers.

 

[KsM715]

Pull the intank pump and check the line that draws fuel out of the tank. sometimes those lines are rotted and cracked and broken and will not pull fuel out of the tank.

 

[deucesarewild]

OK good I will check the lines in tank. Thank you everyone for the quick and helpful input. Also on a side note I had someone argue with me that not all deuce multifuel trucks have an intank electric fuel pump is this true?

 

[gimpyrobb]

Open the bleeder port on the filters bolted to the side of the motor.
Turn on truck power.
See if fuel sprays(or leaks) out of the bleeder.


If not, you have an obstruction in your fuel supply.
Start at the fuel pump(in tank) and work your way to the IP. Make sure you test/check EVERY component on the way.

Welcome to the site.

 

[phil2968]

I'm surprised no one has asked. How much fuel is in the tank? Some of the intank pumps are above the bottom by a little bit.
But yours is full correct?

 

[doghead]

A cushed fuel line under the radiator crossmember, is common.

 

[swbradley1]

After checking what Gimpy said you can put a pressure gauge on the port on the top of the fuel tank (hex head port) and see if it is working there when you start troubleshooting. Yes, the line runs right under the front cross member and I guess it could get crushed at that point. It must not be that susceptible to crushing or a lot of people would do it at Haspin hitting the holes.

It is possible that a MF might not have an in-tank pump, especially if they have replaced it with an external electric pump like:

Airtex 110-E8131 - Airtex External Electric Fuel Pumps - Overview - SummitRacing.com

 

[deucesarewild]

Yes tank is full of diesel . I will check the fuel line from tank to IP, and the bleeder port, wont get to work on it until Saturday...thanks for all the replies

 

[WantOne]

You could bypass everything up to the IP by having a 3' hose made that will connect to the IP putting the other end in a can of clean fuel. IP should be able to pull fuel from that tank, and if it then keeps running you've isolated the issue to the fuel tank/pump, primary filter and lines that lead up to the IP.

 

[Emmett]

You said you primed the filters....Just how did you do that?
I can only assume you fill them with fuel and tried to start the vehicle. To Prime the system, You need to open the bleeder with the ignition switch on thereby letting the in-tank pump to push the air out of the filters.
If your in-tank pump is inop, you can not prime the filters without pressurizing the top of the fuel tank thereby pushing the fuel up to the filters.

 

[gimpyrobb]

You could bypass everything up to the IP by having a 3' hose made that will connect to the IP putting the other end in a can of clean fuel. IP should be able to pull fuel from that tank, and if it then keeps running you've isolated the issue to the fuel tank/pump, primary filter and lines that lead up to the IP.

What I posted will do the same thing, with less effort.

 

[DeucesWild11]

Can you hear your fuel pump running when you turn the main switch to ON? I can usually hear mine if the Air warning buzzer is not going on. If you have the buzzer going off just unplug it, it's under the dash on the firewall. Then you should be able to hear if it's turning on or not.

 

[frank8003]

Fuel pressure Deuce

Open the Primary filter drain to a bucket and operate accessory switch ot ON. Should get lots of fuel there. Now you just cut the problem in half. Problem is before or after the Primary filter.
If problem is before the primary filter than
go to the fuel tank. At the tank at the output line to the truck look on the outboard side of that fitting for the hex driven pipe plug. Remove the plug and stick a gauge in there or a hose to a bucket. (1/8" NPT) One can not hear the in-tank lift pump if the low air pressure buzzer is on so just see if the pump is pumping first. Should have 3 to 7 psig ? there with a stock pump.

Or all the other suggests are really good too. I especially liked the primary filter output 3/8" line across the front of the truck under the radiator being squashed. Are they all squashed like mine?