XM818 fuel issues

[sermis]

I have Kwai's truck and trailer here. Once loaded with tires for Rizzo and Redass73 and other things along with my CJ5 I will be taking it to Houston. I noticed the truck still has some fuel issues. We discovered that the fuel shut off was not returning to run when the cable was pushed back in. The truck is still really hard to start. Will not start with out using the primer pump quite a bit. I also noticed that when I push the go go peddle it is like the engine needs to think about it for a while before the RPM’s start to climb. Coming from San Antonio it did fairly good and would hold 2,100 RPM except for going up hills. At Idle I noticed that it had a little serge of RPM’s up and down.

 

[Kwai]

I noticed the surge at idle as well. Injector pump or dirty injectors?

 

[Scrounger]

First off the emergency stop is just that and is meant to be reset by opening the hood and turning the valve. Yes you can move the stops on the cable to be able to reset from the cab if you wish, however the 800 series trucks have an electric solenoid for shut off.
As far as fuel issues, there isn’t an in tank fuel pump so the 800s are picky about air leaks. If any of the rubber fuel lines from the tank selector valve are cracked you can bet there is an air leak. That will also make the truck loose prime when parked, sluggish when starting and even cause a surge. Even when running right one can expect a little surging till the truck warms up a bit.

 

[timntrucks]

yes that sounds like a air leak. make sure the drain line is tight and check to see if you dont have a square washer on top of fuel filter. if so that MUST go down into the square slot or oring will not seat. its not on all but on some Tim

 

[jwaller]

you will more than likely need to replace every single flex hose in the fuel system. I had to do it on mine. that means all 6 on the fuel selector valve. 2 or 3 under the hood and make sure the lines on the tank are tight and the filter is tight with a good new seal and filter.

just bc it doesnt leak fuel on the outside doesnt mean it wont suck air when the motors running.

my xm818 will start so quickly you cant get you hand off the starter switch soon enough.

you should also check the fuel filter on the pump for contamination too.

never use the cable in the cab to shut down the motor. if you have you must go under the hood to reset it.

to shut it down just turn off the switch on the dash.

 

[Kwai]

Sermis, looks like we have some plumbing to do. What size are the rubber fuel lines? The fitted line from the filter to the fuel pump looks new.

 

[DaveP]

Will Wagner told me the screen on the pump was only there to capture particles in case of pump failure.

 

[jwaller]

Will Wagner told me the screen on the pump was only there to capture particles in case of pump failure.

that too is what I heard. but it's no reason not to check it. it's an easy job.

there are several different sizes of fuel lines and if I remember right some were 9/16 and other are 11/16

 

[halftrack]

As far as fuel issues, there isn’t an in tank fuel pump so the 800s are picky about air leaks. If any of the rubber fuel lines from the tank selector valve are cracked you can bet there is an air leak. That will also make the truck loose prime when parked, sluggish when starting and even cause a surge. Even when running right one can expect a little surging till the truck warms up a bit.

This could not be more true. Going through the exact samething with the M813. Real Hard to start but when running it is the strongest MHC 250 I think I have. It looses prime everytime though after it is turned off. I believe it is sucking air from a fitting on the pump somewhere. Very frustrating.

By the way, which fitting on the pump shoud I crack open if I want to push the air out and make sure it is primed with fuel?

 

[sermis]

I noticed that when we tried to bleed the air from the system using the primer pump it pulled all the fuel from the filter can. I think the air leak is somewhere before the filter can. Yes it has the square washer on the bolt that holds the fuel can on. I was thinking it could leak air from that but was not sure. I tried to put a second “O” ring between the head of the bolt and the square washer but it rolled out when tightened up.
There is a new fuel line from the filter can to the injector pump. I am guessing that they were having fuel issues with it when it went to GL.
On the plastic spaghetti lines are there any special fittings? Can they be had at Lowe’s? Will the plastic line from Lowe’s work for the fuel lines?

 

[73m819]

at the fuel filter, there are TWO petcocks, one is the water drain at the bottom of the filter, one if just before the filter on the tank side, make sure these are tight, thay may be tight but have crud in them (especialy the bottom of the filter one) where thay dont leak fuel but will leak sucked air, the easest way to check for sucked air leaks is to pressureise the fuel system , eather from the tank(no more then 2 or 3 pounds) or from a tank fuel line disconnected from the tank connected to a electric fuel pump and drawing from the tank

 

[sermis]

I noticed that there is fuel leaking out around the primer pump rod when it is pumped. Can it pull air into the system from there?

 

[beaubeau]

That should not affect fuel system if it is screwed closed after U pump fuel with it. Does this thruc run well when started? Be sure ALL Air is out of system! Good Luck, Phil

 

[73m819]

in fact my o-rings died on my primer pump and had fuel dripping on my foot, the 0-rings are a strange size

 

[jwaller]

I noticed that there is fuel leaking out around the primer pump rod when it is pumped. Can it pull air into the system from there?

yes this is a problem. I found the orings at my hardware store. took abuot 5 min to change them. You will need 2 and mine was dripping on my foot too.

 

[sermis]

Have not noticed it dripping except when pumping.

 

[texas-5-ton]

Have not noticed it dripping except when pumping.

I had air leaking here too and it caused a huge problem. I'd say this might be where your problem is.

 

[alphadeltaromeo]

I'm just glad ya'll are getting this stuff figured out for when I go to pick up my M818...all the learning is good for me!