Problem bleeding bosch fuel injector pump

[jrchafin]

Hello all, have a Mahindra 7520 with 700 hrs on it, about 6 years old.

Using it the other day and I noticed a diesel fuel smell, found a leaky gasket in the bosch injector pump. The leak was on a gasket underneath a plate that was facing the engine block, so I had to take the pump off to fix the gasket. I have no idea why this started leaking, but it was running fine otherwise.

I removed the pump, and replaced the gasket as well at the other gaskets involved in the removal. I reinstalled it, and cracked the line that enters the pump, running through the filters and hand pump to the top of the injector pump. I hand pumped until fuel came to this point and then re tightened that line.

I knew the pump wasn't bled completely, but decided to try and start it. I cranked it and it ran great. put it at full throttle for a minute or so, no problems, no leak. I shut it down thinking I was done.

The next day it wouldn't run at all, just cranks and cranks with the starter, a little grey smoke coming from the exhaust. I figured I was air locked, so I removed the high pressure lines and tried to hand pump fuel through the pump. I have pumped that thing probably 50 times or more, and it feels like it's pumping, I can hear a hiss, but no fuel comes out of the high pressure ports.

What am I missing?

Thanks in advance.

 

[Winmac]

You must crank the engine over to get fuel out of the high pressure side, the hand pump only fills the body of the pump, when you open the bleed screws.

 

[Raised on a Deere]

You must crank the engine over to get fuel out of the high pressure side, the hand pump only fills the body of the pump, when you open the bleed screws.

Not sure if your system is self bleeding or not but even after filling the pump with the hand pump you may need to crack the injector fitting loose to allow air to escape while you are cranking the engine. Open just a "smidge" and close immediately as the engine starts running. It will smooth out quickly after a rough sputtering start. Just be careful to not get you hands in the path of squirting fuel. It is under very high pressure. I place a rag around the wrench that is spanning the fitting and tighten immediately as the engine sputters. Hope this helps

 

[jrchafin]

Thanks guys. Got it running, and this time it promptly started leaking again. :-( Now I have to figure out what is wrong with this pump. Seems it is building up excessive pressure and blowing this gasket out.

 

[Raised on a Deere]

Thanks guys. Got it running, and this time it promptly started leaking again. :-( Now I have to figure out what is wrong with this pump. Seems it is building up excessive pressure and blowing this gasket out.

I have a Dexta (3 cyl perkins) that the pump started leaking and while trying to find a fix, I attached a made up metal container held in place with baling wire and let it catch fuel. Emptied it into tank two or three times a day. That temporary fix became the permanent as that is the way she still sits. Don use that tractor much any more. No power steering and no spring in seat, no loader, -- What good is it??:laughing: But for about ten years that is the way I kept my place mowed.

 

[jrchafin]

Anybody else have this problem? I don't want to just replace the gasket only to find that it blew out because of something wrong with the pump and do more damage. Maybe it's building up excessive pressure? I shouldn't just have a gasket failure on such a new pump without another cause. I've heard some say it's the new diesel fuels.

 

[Winmac]

Can you describe which gasket was changed, I'm not sure from your earlier description which it is. Picture might go a long way.

Pressure in the body is regulated around 70-90 psi max, but it could over pressurized if there are issues. I'd be tempted to replace the gasket again, did u use oem? Often they are special material

 

[jrchafin]

Good idea Winmac. Its the shiny plate at the bottom in the pic labeled Y330. This is the right side of the pump as it sits in the tractor, against the engine block.

 

[jrchafin]

My pump is a bosch VE type pump. Found this article that shows a larger version of the same basic pump, and it apparently has a max fuel pressure of 17,400PSI! I don't know if I'm getting that much pressure, but that would explain a lot, the special gasket, blowing out a regular gasket in no time, 1/4" grade 8 steel cover plate.
Injection System Basics - Diesel Power Magazine

 

[skyhook]

Sounds like you need a pump rebuild.