Need Help Diagnosing Fuel Delivery Issue

[WWRD99]

Yeah i plan on posting pictures of the pumps later - the one i pulled off of it that i got a replacement for is the incorrect one that does not work. But you can see when comparing them that both the plunger arms are still slightly different, even though they are the same style, which makes it even weirder that it worked for so many years .......

After putting on the correct one last night, i got fuel to the filter within about 10 seconds of cranking.

And i have a big boster charger hooked to the batteries that i turn on whenever i am going to try to start it. Havent left it on overnight as i worry about it getting hot.

Mine has been converted to 12 volt too

Yeah the difference is the arm angle. They look identical at a glance and most don't think about it. So it's 12 volt...did they change the battery cables to a larger guage? If you have a 10 or 20 amp setting and good water levels they should be fine. Check the starter for the front bracket if you haven't already. They have to change the starter in the conversion...might have left it off.

Sent from my SM-S906U using Tapatalk

 

[huskerfan]

Yeah the difference is the arm angle. They look identical at a glance and most don't think about it. So it's 12 volt...did they change the battery cables to a larger guage? If you have a 10 or 20 amp setting and good water levels they should be fine. Check the starter for the front bracket if you haven't already. They have to change the starter in the conversion...might have left it off.

Sent from my SM-S906U using Tapatalk

I believe they did yes. Like i said, it has ran fine for years with no issues lol

And yes i have replaced the started many times with the gear reduction one as i usually go on 2 river trips each year and the starter isnt a fan of being swamped in 3-4' of water, but O'reillys and their warranty always comes through lol

 

[Barrman]

Yes, I am the Tim in the video.

Delphi HFP906 is the only mechanical pump I know currently sold new that works and can deal with the biodiesel.

 

[huskerfan]

Well guys plugs was an issue. Pulled them all and only 1 of them didn’t ohm out. Put all new ones in and finally got it to fire up and run but had to massage the throttle a little to get it to stay running. But if I gave it a lot of throttle, once I let off, it would die. It’ll fire right back up, but idles rough, and if you give it throttle, it’ll die when you let off the pedal, unless you let off really really slowly. Here’s a video:

IMG_0974.MOV

drive.google.com

I even switched the fuel pump line and ran it to a Jerry can full of diesel to rule out anything upstream, but had the same issue.

anybody got any ideas on what to check next?

 

[WWRD99]

Well guys plugs was an issue. Pulled them all and only 1 of them didn’t ohm out. Put all new ones in and finally got it to fire up and run but had to massage the throttle a little to get it to stay running. But if I gave it a lot of throttle, once I let off, it would die. It’ll fire right back up, but idles rough, and if you give it throttle, it’ll die when you let off the pedal, unless you let off really really slowly. Here’s a video:

IMG_0974.MOV

drive.google.com

I even switched the fuel pump line and ran it to a Jerry can full of diesel to rule out anything upstream, but had the same issue.

anybody got any ideas on what to check next?

Did you put the clear fuel line on the ip return yet?

Sent from my SM-S906U using Tapatalk

 

[huskerfan]

Did you put the clear fuel line on the ip return yet?

Sent from my SM-S906U using Tapatalk

Doesn’t that just tell us if there is any air in the system?

 

[WWRD99]

Doesn’t that just tell us if there is any air in the system?

Yes

Sent from my SM-S906U using Tapatalk

 

[huskerfan]

Yes

Sent from my SM-S906U using Tapatalk

I had an injector line cracked when i fired it up, wouldn't that have gotten most of the air out?

 

[WWRD99]

I had an injector line cracked when i fired it up, wouldn't that have gotten most of the air out?

Not at all. The other 7 would need cracked if you wanted to get all the air out.

Sent from my SM-S906U using Tapatalk

 

[huskerfan]

Not at all. The other 7 would need cracked if you wanted to get all the air out.

Sent from my SM-S906U using Tapatalk

So i should put the clear hose on there and see if there's an air bubble right?

Does going through and cracking all of the other injectors get me anywhere? Seems i remember reading on a thread on here about the clear hose, but not really about guys needing to go through and crack injector lines individually.

 

[WWRD99]

So i should put the clear hose on there and see if there's an air bubble right?

Does going through and cracking all of the other injectors get me anywhere? Seems i remember reading on a thread on here about the clear hose, but not really about guys needing to go through and crack injector lines individually.

The clear line shows bubbles and very nice to have the knowledge that it has air in the fuel or not. No guessing. You do need to crack every line a bit to get the air out. If you can get it running and have someone hold the throttle up some and crack each one quick it won't take long.

 

[Barrman]

The die when you let off the throttle but start right back up again thing.

I have experience with several trucks where the only cure was an injection pump rebuild. 100% success fixing the problem.

I also have about 50% success with new fuel, filter and just run the truck on the road at least a few miles everyday. But if it is so bad that just letting off the throttle when topping a hill turns off the engine. It is normally too far gone, get a rebuild.

 

[huskerfan]

The die when you let off the throttle but start right back up again thing.

I have experience with several trucks where the only cure was an injection pump rebuild. 100% success fixing the problem.

I also have about 50% success with new fuel, filter and just run the truck on the road at least a few miles everyday. But if it is so bad that just letting off the throttle when topping a hill turns off the engine. It is normally too far gone, get a rebuild.

It's just so weird to me that this randomly started happening one day at an offroad competition. I thought if the IP is going out, the symptoms of that slowly come about? My truck has never just died while running. I remember it vividly because i didn't even realize it had shut off i was so shocked by it. But then it would keep dying as soon as i would let off the throttle the rest of the competition and ever since, which was back in November

 

[Barrman]

Pull the check valve in the return line on the top of the injection pump. Look inside and see if there are little black bits in there.

 

[huskerfan]

Pull the check valve in the return line on the top of the injection pump. Look inside and see if there are little black bits in there.
[/QUOTE]

Already tried that and there were no little black pieces or anything - i could see light through the little glass ball