injector pump pressure on yanmar 2GM20FC

[summer love]

I am in the misleading of diagnosing an loss of rpm from 3600wot to 3400, to a pulsating 2000/2400 rpm over a two month period....the situation is that in gear it pulsates from 2000 to 2600 rpm sometimes.....holds at 2400....then pulsates 2000/2400 in forward gear...replaced filters, ran without air filter with no change...the weird thing, in reverse, rpm to 3400.....probably due to lower water flow restricting prob from turning....am in the middle of cleaning the injectors...compression at 425psi each cylinder...what is the injector pump pressure to the injectors...when I apply 80 psi to each removed and cleaned injector, they begin to open at 80 psi?

[DougR]

The 2GM injector opening pressure is 170 kg/cm2 ....plus /minus 5.
Thats between 2347 PSI to 2489 PSI.

DougR

[Wotname]

Welcome aboard CF, Summer Love.

How old is the engine and how many hours are on it?

[GordMay]

Greetings and welcome aboard the CF, summer love.

[summer love]

the reason I was looking for the pressure is to check the injectors I just repaired, and I found the answer.....it is 170 psi...a search on YouTube showed the tester used for this injector to pulse it repeatedly at 170 psi.....thanks to all who have assisted in this

[Sailmonkey]

Originally Posted by summer love

the reason I was looking for the pressure is to check the injectors I just repaired, and I found the answer.....it is 170 psi...a search on YouTube showed the tester used for this injector to pulse it repeatedly at 170 psi.....thanks to all who have assisted in this

If you've got 170 psi cracking pressure on your injectors you've got big problems.

[DougR]

You might want to recheck your numbers.....the injectors are supposed to open at 170 alright, but it's not PSI....its kg/cm2.. Kilograms per centimeter squared, and that equals 2418 PSI.

DougR

[summer love]

Doug you are correct.....I have fuel pressure to the injector pump....where I opened the bleed valve and fuel pressured out..but nothing from the injector pump...in figure 57 FUEL CONTROL DEVICE..what function does the adjustment screw serve, and how does one check its setting..this could be the culprit or the joint bolt screw that the injector bleed valve screw is attached to.

[summer love]

fig 57

[summer love]

I guess fig 57 didn't upload....back to the drawing board

[Sailmonkey]

Are you sure your fuel rack (throttle) isn’t stuck? Or the shutdown lever (that pulls the fuel rack to zero delivery) isn’t stuck or pulled?

And are you checking for fuel at full throttle? At idle the fuel delivery will be minimal

[Tornadosailing]

I helped a guy fix similar issues with his Catalina. Turned out to be a porous fuel hose between the tank and the lift pump. He had no fuel leak, just a tiny bit of air being pulled into the line when it was running. Being an '82 it might be worthwhile to give all the rubber parts a good inspection.

[summer love]

the shut down lever is where it should be....going to backout the adjustment screw item 6 from above, l think that someone poking around lately may of turned it in, causing the shutdown lever to engage thus not permitting the pressurized fuel from the secondary fuel filter to enter the injector pump.

i am using an outside fuel tank hooked up directly to fuel filter, it ran the same way...max rpm in gear 3000 pulsating to 2000, in neutral 3400, then the neutral adjustment screw was touched, now nothing from injector pump.

going to boat today to further test...if injector pump is the culpret, what hidden problems may arise from its removal...internal attachments?...

[summer love]

ok the first thing I did was to back out the neutral adjusting screw....this allowed pressurized fuel from the secondary filter to enter the injector pump...then I opened the injector pump bleed screw to remove any air..then I opened the compression levers so I could bleed the injectors...then I opened the injector fuel feed pipes so as to bleed lines...done..closed compression levers, tightened feed pipes, closed petcock, engine started immediately, opened seacock, site idle to 1300rpm.....throttled up to 3000 max, then the engine took over...back to 2000rpm, pulsating to 1500rpm..after 3 minutes died...ok frustrated at this point it is obvious no fuel...but from where..opened the secondary filter...dry to the bone...put filter back and manually primed till bowl filled and injector pump and injectors purged, restarted with the same results....empty secondary fuel filter...ok air leak somewhere, or leaking fuel pump...removed fuel line for replacement, noticed detoriation at pump input, cut off 2 inches reinstalled, bled system, started engine.....runs perfectly up to 3400rpm.. in gear..30 minutes..no oscillation......you never know

[Tornadosailing]

Glad you found the problem. I trust you'll be replacing all of the rubber fuel hose in the very near future.