Genset No Fire/ Fuel Pump

[spartonboat1]

Splashed and was starting all engines. Genset, Onan MDJE 7.5Kw, started instantly, ran 10-15 secs, stopped and would not restart. I will be pulling the primary fuel pump, as I think that is the issue. But before I do in a few days, thought I would post here, for further ideas.

I pulled the water cup, which is integrated with thy primary pump, and found some kludge particles on the cup bottom, but the diesel was clean. So cleaned the cup out, re-filled with fresh diesel, re-installed. I worked the priming arm quite a few times, 20-30+, but the arm never seemed to meet resistance; not sure if it should (?). While trying to re-start, it would fire a tiny bit, but never catch.

My guess is that the diaphram split/tore in the mechanical pump, when I first started, because it ran so well, then stopped and would not restart.

Will post update on results, at later time.

[ncfathom]

Hard to tell what is happening at this point. If the cam lobe has the pump engaged you will feel no resistance on the lever. Turn the engine 1/2 turn and pump,crack a bleeder or injector line and see if you get fuel. If so,proceed to bleed. If not,look elsewhere. Check in logical order. Fuel in tank? Valves between tank and filter? Lift pump working,etc. They only way to troubleshoot. Good luck.

[wmfels]

let us know what you come up with, i have the 7.5 also and is a PITA to get started, and gives off black smoke, my buddy i was tied up with wasn't too happy afer i pulled away from his boat. i did notice the fuel pump is leaking now so possibly sucking air?

[chris piazza]

Yup sounds like your on the right track. The lift pump has a diafram in it and you should feel a little resistance after about 30 strokes. Rebuild kits are available for the Lift pump as I had to do mine last year. Be careful as you take it apart because there is a lot of small pieces that "spring" out, don't ask me how I know this. After about 1/2 hour you should be done.

Chris
Superior Nights 53C

[spartonboat1]

let us know what you come up with, i have the 7.5 also and is a PITA to get started, and gives off black smoke, my buddy i was tied up with wasn't too happy afer i pulled away from his boat. i did notice the fuel pump is leaking now so possibly sucking air?

If you have a "normal" 7.5, then you should have one starting aid per cyl, i.e. each cyl has a "glow plug". Also there is a "heated coils" unit (I call it the toaster oven) that is in the air intake that serves both cyls. That "toaster oven" has two internal heated coils, either of which can go out (or both). So there are four points of starting aid that may go out, any one of which reduces starting ease.

So if you do it yourself, put meters on the two glow plugs with the Ohmmeter and each should get a reading. Also do the same with the two heater coils, which should have a reading (register a value).

I was frustrated with the Hatt Dealer/Marina Manager who said my Onan "...was shot...", because it started hard and smoked. Those guys gave me lots of bad advice. Actually, it needed a glow plug and a heater coil each replaced. That Hatt manager helped them get one of the poorest reps in the Midwest; I won't be more specifiic, because after 4 attempts (new managers), they seem to now have a good manager (one of their own in-house guys).

Finally, its possible the primary pump is weak as well.

M2CW...

[spartonboat1]

Hoping to pull primary fuel pump in the next couple weeks. One reason that I moved the boat 4 hours closer, so I can give it some TLC, sinced I like to do some hands on. Frankly, where I was before, good techs were very hard to come by. It is super nice to have her closer by.

[ocburger]

I had the same problem. I replaced the fuel pump with an electric from napa for $20 bucks runs perfect. I wired it to the started circuit so it turns on when you preheat or start. You never need to fool around with that lever again.

[spartonboat1]

I had the same problem. I replaced the fuel pump with an electric from napa for $20 bucks runs perfect. I wired it to the started circuit so it turns on when you preheat or start. You never need to fool around with that lever again.

As the saying goes, "...did it/does it bolt into place..." of the old/legacy pump, or did you leave the old one in place and mount the new one elsewhere....etc.?

[gbharrington]

I also replaced my pump with an electric one. The shematic indicates an optional electric pump that is wired to the same circuit as the as the fuel solenoid. I also added an inline filter before the pump.

[ocburger]

As the saying goes, "...did it/does it bolt into place..." of the old/legacy pump, or did you leave the old one in place and mount the new one elsewhere....etc.?

I left the original in place. The electric pump is about 2" in diameter and 4" long so it looks like a buldge in the fuel line. Comes with a bracket I attached to one of the bolts on the gen vent cover thing. With the correct fuel line connectors probably 30 min job.