Cummins 4BT & Diesel Conversions Forums banner

4bt injection pump leaking fuel......

35K views 40 replies 9 participants last post by  omegalpha82 
#1 ·
Hey all, I have a 4bt powered M715 that I put together this summer, and long story short, she started leaking diesel from the injection pump last week. I don't have any pictures available right now, but it is leaking from the manual kill valve? A spring loaded piece located on the left hand side below the throttle. Also, I have been using this regularly since my fuel cut-off solenoid hasn't been working since I got the truck together. I will try to get pictures up later, but has anyone had this happen before?

Also, I remember having found a website that offered pump rebuilds for I believe about 250 bucks, it may be time for that in my case does anyone know who these guys were? I believe they also did entire swaps.

My truck is the lower hp version btw.

Thanks,
Steve
 
#5 ·
I just replaced my uperseals on my pump and only cost $30 for the seal kit. When I reinstalled it leaked at the same seal you are talking about and found that I used the wrong o-ring. I was able to replace this seal though without removing the pump again though. You can try replacing the seal without removing pump just don't lose the timing of the kill lever when you reinstall it.
 
#6 ·
Hey, thanks for the responses everyone. I think my best bet will be to start cheap and work my way up. So I'll start with a reseal kit and see if I can get her to stop leaking. Here's a pic of my pump incase anyone is interested and the kill switch leak area is directly behind the baffled throttle cable in this picture.



The_New_Kid, any pointers on not losing the timing of the kill switch? I assume that I just remove the end nut on the center and it will start coming apart?

Thanks again,
Steve
 
#7 ·
Well, I finally have gotten some time to work on the truck and the leak is not from where I originally thought. In the photo below it shows the diesel leak and is at about 1 drip every second. Also, the truck lost its prime over the past four weeks since I last ran it. I have a seal kit in hand but my question is should I just disconnect the injector lines and pull the rear of the pump? or pull the entire thing? in which case how do I make sure not to lose my timing. Any comments/help would be greatly appreciated.

-steve
 
#9 ·
I understand that. However I am having trouble finding a shop manual online and was hoping to get the truck up and running by the weekend. So what I was hoping to find out here was either where I can get a shop manual detailing dissasembly in an online format so I can view it now. Or if someone could just tell me whether or not it is even possible to remove just the rearmost section of the pump where the inlet valves mount?

-Steve
 
#13 ·
Thanks for the help so far everyone. I got the seal replaced today and reinstalled the pump but had some trouble getting a prime, Pumped that little handle about 100 times and still no dice so I'm hoping that I put everything back together in the proper manner, but we'll see tomorow when I have more time to play with it.

-Steve
 
#14 ·
The transfer pump with the little handle is driven off the cam shaft. If you dont feel any resistance when pumping that handle, its possible that your on the high lobe of the cam. Bump or bar the engine some, this will rotate the cam and now allow you to manually hand pump fuel to prime. If your on the high lobe, all the pumping in the world...is NOT pumping fuel. When the cam lobe is low, you will feel a noticeable difference when hand pumping.

Paul
 
#15 ·
Yep, that's what I noticed about the pump. It's still giving me problems though. I have a full tank of fuel. When I disconnect the fuel line to the lift pump fuel drips out so long as it is below tank level, and sucking on the line produces a mouth full of diesel. Nonetheless, my lift pump just isn't pumping. I feel resistance and can hear the internals moving, yet there is no fuel leaving it. I disconnected the lift pump output to verify this and am just not getting any movement. I'm going to search the forums to see what I come up with, however if I can't get her running today then I'll be driving back to school in another vehicle and won't be back for a few weeks so may just order a plunger style lift pump.


Any comments/suggestions are extremely welcome.

-Steve
 
#17 ·
Well I got the new pump and still no dice. We also got 8 inches of wet snow last night so I am very close to calling a tow truck and finding a CT diesel shop that can take care of this for me.....

Situation pretty much is I installed the new pump, primed it and had fuel flow at the filter as well as feeding into the pump. I then cracked the lines at the injectors and primed it 60 times. Tried starting, no dice. Primed it 75 times still no dice. Coming out dry at the injectors, I checked the fuel shut-off solenoid and it has spark and clicks when I cycle the key. This may be a stupid question but should I be able to hand prime her to a point where I have diesel at the injectors? my inclination is to say no but I honestly am not sure.... Thanks, Steve.

Also any shop suggestions near by or a traveling mechanic would be appreciated....
 
#18 ·
Just because the Fuel Solenoid clicks, does not mean its opening.
I would pull the fuel shut off solenoid and remove the plunger and check its condition. Maybe its stuck closed, maybe the small rubber sealing end has come off and is blocking the fuel system. If either happened, the solenoid woudl still click, but not admit fuel. When the solenoid is removed take out the plunger and put the solenoid back on the IP and try starting. If it goes, you know the problem is in the fuel solenoid. You can shut her down with the manual shut down lever.

Paul
 
#19 ·
Thanks for the response Paul. I feel like that could also be the problem. I tried to get the solenoid out however just ended up coming inside frustrated.... The top of the pump blocks from view what I am doing and the damn pump bracket doesnt allow me to get a wrench on it, nor do I even know the correct size, somewhere around an inch/20+mm.

I should note though, that my fuel solenoid has never been able to shut the truck off before and I have always relied on the kill lever....... if this fixes it then that would be a little bit of a kick in the nuts for not figuring that out sooner.....

So, I'm going to search for some tips on removing that bitch, because pulling the bracket requires removing 5 of the 6 pump head bolts (not what I want to do) or busting out the plasma torch and taking off some of that bracket..... the engine is however coated in diesel/oil so that's not ideal either......
 
#20 · (Edited by Moderator)
Well..... I just got the solenoid out and gutted it, reinstalled. Then put a piece of cardboard behind the outputs on the pump and cranked her. No dice, two baby squirts but nothing when cranking for sustained times. I think this may have become the 1000 dollar fu**ing drip..... Looks to me like something did not go back together the way it should have and hence the rear valves aren't firing. When I pulled the solenoid there was diesel in the hydraulic head by the way... :(
 
#24 ·
nope thats everything.Check it to make sure it works outside the vehicle.It should pull up into the solenoid.I think you still have air in your lines.You have a new lift pump now?It should be putting out 7psi(check by tapping the banjo at the filter head)Take the lines off of the pump and get someone to watch as you crank.You should get good spurts of fuel(past the lift pump) coming from the delivery valves.If not youve got a high pressure problem.Makes absolutely sure youve got fuel in the IP.Double check your tank fuel connections most problems start here
 
#25 ·
Thanks ,

Yes, I have a brand new lift pump that seems to be working well when I hand prime it. I'll try to find a gauge though so that I can setup and test the fuel pressure today. Beyond priming the lift pump though and cranking the engine what else can be done to get the air out of the lines?
 
#26 ·
Take the lines off and make sure its shooting fuel.If not theres other problems.If its fully primed and shooting fuel then you just have to crank longer with the injectors cracked.Ive had a pump that hardly needed any priming but i have one now thats a nightmare.
 
#27 ·
Hey thanks again for all the help thus far gentleman. Today I played around bleeding it some more and this is what I found.

I have fuel out of the fuel filter bleeder and got rid of some air.

I also cracked the fuel return line and got fuel with no bubbles from that when priming.

then I put some cardboard behind the injoector line outputs and cranked it for about 5-10 seconds and found diesel about the size of a quarter from 3 of the 4 injectors.

So from there I reconnected my lines, cracked the injectors and started cranking. I've been cycling it to avoid burning up my starter. I do 20-25 seconds cranking with two minute breaks and time it out on my watch. I did 7 cycles today and still no diesel at the injectors.

I know there is diesel at the shutoff (now gutted) and at the return, and atleast some was coming from the injector outputs.

I plan on trying to crank it a bit more and seeing what happens, but am curious about all of your input on this?

Thanks,
Steve K
 
#28 ·
Ok.... I tried and I tried..... still no dice. I must not have put something back together correctly. So, I started pulling the pump again tonight and will finish up after dinner tonight. Then tomorow morning I can run up to Mass Diesel and drop it off. They said it should be done by weds or so. Cost is unknown but they'll get back to me while I'm enroute.... The problem is I just don't know enough about these pumps and I need the truck kicking by next weekend. So I'll let the pump win this time.

BTW, what mods should I have done while they have her apart? I am running 35 turbo and think she could use a little more go.

Thank you all so much for your help, I definitely learned a lot about my truck and a little about my pump.


-Steve
 
#29 ·
if it was shooting fuel out it should have primed!Did you take it apart before entirely?All lines were cracked open?
 
#31 ·
Hey all, I honestly think that the problem was with my pump and not so much the priming. Everytime I chased the air around cracking lines, return, fuel filter bleed, I never saw air, just fuel. And to be honest it was my first time pulling apart the pump. As far as removal/install, I used the Cummins manual that was linked earlier in the thread. The TDC pin is a very cool idea btw.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top