[Archived]

Well since you cannot blame the spark plugs or points the only thing left if it runs well otherwise is fuel.

I strongly suspect some how, somewhere in the system fuel is leaking out and is being replaced by air. When you step on the throttle you are reintroducing fuel to the system and it is then getting to the injectors.

Do you have any evidence of fuel in the oil?

Maybe Clifford can lend his expertise here. He is the 2 stroke guru.

[Archived]

Probably the check valve mounted on the filter and like Jon recommmends check for fuel in the oil the o-rings on the fuel tubes go bad or come lose then it could also be the injectors dripping do you have white smoke on start up ?

good luck

[tom]

Do you have any flexible fuel lines from frame rail to engine. They have been known to seperate internally, due to age, heat stress.

[Robert]

When the erratic start happens it does seem to be starving for fuel and actually skips on a few cylinders and then smoothes out. I agree with the idea of air getting in the system somehow and that is one of the reasons I installed the electric fuel pump. But I was baffled when it did the same thing with the electric pump running before starting. I thought the electric pump would keep the system primed. Maybe the mechanical pump pulls more than the 5PSI the electric pump supplies ??? It just seems to me that if there was an air leak the erratic starting would be all the time. It is so hit or miss that it does not correspond to the time between starts, temp or any other thing I can put my finger on. I was wondering if their is a solonoid for the fuel shutdown, or does the fuel shutdown just close the injectors ?

[Archived]

No fuel in the oil,,,,, and yes there are fabric covered lines in the system,,, all are dry. Lots of flow through the system all the way through to the return line. Does not look like any blockage. I keep wondering about the electronic controls. I do not see allot of smoke when starting black or white. Does anyone know for sure what the idle fuel pressure should be,,, measured at the secondary filter ?

[Don]

before trying to start remove secondary filter.. It should be full to the top of fuel…pressure means nothing if it is just building up in this case(shows pump is working)—. while off look at gaskets… make sure there is not a old one left one there by mistake… Just some things to check. Level in filter will tell allot.
by the way the old fuel lines can such air thru them with age… personal experience here. hard find.. don’t jump and change yet do the other things fitst. I found mine by chance-no visable leak but persistant problem I finally pressurized system with air from tank to filter on the 89 XL+= 30lb air air bubbles from soap solution(exterior application) replaced fuel line..Your fuel line is normal a suction line and would suck air in with no pressure to push thicker fuel out until they get to a more detiorated point. Your filter will tell you if you have this problem or any other fuel supply problem before the injectors…Hope this simple explanation helps–I just added the fuel line because of the age of your fuel lines….Bob

[Dave]

Thanks,

I checked the secondary filter and it appears to be full,,, but a few bubbles of air is hard to tell. I am going to replace the fuel lines anyway because I have a hydraulic crimp machine I use for my other equipment and it is not an expensive job. I agree the lines are aged and it won’t hurt. I am going to call Detroit to make sure the 15 PSI is enough for starting,,,, I have read several posts on different sites and some say 30 PSI. idle and 80 PSI at high idle.

Mine is 15 idle and 55 high idle.

[Archived]

is a low dollar (under $150.) easy change. item rite in from of you when your open doors.. sort of a maintance item.. just match the drive like you remove it when reinstall… Been awhile since Ihave changed one but I have always notice a slight drop in power when they start to fail/wear…FWIW

[Corey]

Just got off the phone with Detroit Allison. They say 15 is a little low but should not affect starting. Normally 20 – 30 PSI at idle. They suggested checking the check valve in the Racor filter,,, may be losing prime. I thought adding the electric pump would prevent that so I am not sure how that is possible with the electric pump before the Racor. I am also not sure how the closed system could lose prime even if the check valve were not sealing. It seems to me there would have to be a leak to allow air to get in.

[Archived]

Seem to remember someone on other board finding Racor at fault in past year for problem. You just might be on to something there.

[Archived]

Old post under Chassi H3-40 loosing fuel about page 23 a discussion leading to racor ck valve— on this board– bus was equipped with 8V92—-I tried search function and it did not work…. bob

[Archived]

Here’s the post: http://prevostcommunity.com/forum/threaddetails.asp?Category=Chassis&ThreadID=181

[Robert]

Removed the Raycor,,,,,, full of black goop. The check valve seat or (washer is what it really looks like) was warped and definately not sealing with the check ball. Found a kit at SouthEastern Power but they were 30 minutes from closing and would not wait,,,,,,, will have to wait till next Thurs. I am hoping this is the cause.

Thanks for all the help, will let you know next week.

I am going to pursue the next project while waiting and will start a new thread on running the generator exhaust through the main engine exhaust tip.

Thanks again,

[Jerry]

Robert,

That black gook is algae…

[Charles]

I wondered if it was algae,,,,, I have read about adding a couple of bottles of alcohol to a tank of fuel to dissipate the algae. I know there are all kinds of fuel supplements. I like simple if possible. I have used alcohol in my Bobcat with a Duetz diesel with great success but not sure if Detroit injectors, hoses etc. would be compatible.

Has anyone used alcohol ?