Drove bus just fine yesterday
parked last night
Started this morning just fine
Ran for 3 minutes or so...built up about 30psi
then it shutdown on its own
i checked to see if the shutdown solenoid or emergency flap were triggered (nope)
Tried starting again...it turns over fine just no ignition
Had less white smoke than normal while it was running
Read some posts saying to check the fuel strainer and filter
I cant find them
Where are the fuel filters on a mci7 8v71?
Also last night i wrestled a bike out if storage and jostled the generator diesel feed and return lines.
We have necer run tge generator. Maybe i sent some air into the lines.
Look at the switches in the engine compartment. The one that says front, off, rear start might be on off. That would have engaged the stop cylinder on the governor as soon as it reached 30 psi. The one next to it says engine on, off. Same thing: it controls the solenoid you mentioned, but as soon as you get enough air pressure, it pushes that engine stop lever to cut fuel off. That is more likely than air in the fuel line, or plugged up filters, which by the way, are mounted on the engine cradle rail on the right looking from the bumper.
JC
If you did put air into the fuel lines, you need to prime the system now. There should be a pipe plug on top of each filter (primary and secondary). Fill both filters with a measuring cup and it should start. You might have to repeat one or twice.
An electric fuel pump in line between the tank and the primary filter makes priming real easy.
JC
I started it from the rear. The run/off switch was at run and i observed the shutoff solenoid retracted (run position)
The filters to the right of the engine look like napa oil filters and are oily.
Are they the fuel filters?
Follow the fuel line coming out of the fire wall. It runs to the primary filter. Then to the fuel pump which is on the front of the engine. Then to the secondary filter, then to one head, then the other. Then the return line goes from one head to the fire wall and back to the tank.
The 2 filters closest to the bumper would be fuel, and the other one closer to the firewall would be oil for the engine. Previous owners might have changed things around, so don't take my word for this, look at how the lines come and go.
Do you have a maintenance manual and a parts manual for your bus? You really need them if you don't. A DD V71 series service manual for the engine is good to have too.
JC
Thanks a bunch. I have the mci partsmanual and maintenance manual. The assembly looks right but the actual filters pictured look different. Ill lookup the napa number and see.
where can i find a good dd 8v71 manual?
Sorry for the basic quedtions...im newe ti buses.
Ok found them, they are napa 3118 and 3120 fuel fikters. Now they are on there tight, cant get them off.
More elbow grease i suppose, any tips?
Strap wrench....also, fill the new filters with fuel before installing them.
Does it start and run with a small shot of ether?? Not a good practice, but it may narrow the possibilities...
Don't forget....a small shot only......and only 1.
Shot of ether made no difference
Shutoff fuel input petcock
Got the secondary filter off and it was full / spillingover
still cant remove primary filter
When you put your filters back on, don't over tighten them......which might be why you are having trouble getting the primary off. Get a good filter wrench, the chain type is best.
If the secondary is full then you don't need to worry about the primary.
Ignore me, I'm following thread, :)
If your saying that a shot of ether does not make any difference, it would seem to be an air problem rather than fuel.
If the genset lines are Tee d into the main fuel line its sucking air from those lines tha got ripped loose
Rick 74 MC-8
bobofthenorth - that is good to know - however, i dented the primary trying to remove it with a strap style wrench - so im putting the new one on
Lin - i wasnt sure if it would fire with ether only - but i would expect a good amount of white smoke if it was getting diesel and not air (am I right here?)
Rick - that seems to make the most sense - i am not sure if they are tee'd to the main (return or supply) - cant wait to trace those hoses (they go directly into that center channel [old walkway])
So I need to replace the primary filter (and fill it with diesel before installing).
Do I need to prime the fuel system after this? I have heard that sometimes the pump looses prime.
Should I isolate this issue of "losing prime" by removing the return line at the firewall and checking for fuel while starting?
Dlsnow - One thing I have done recently is started the bus and not had the ignition turned on. The bus will start, run for a minute or two and then not start back up as the ignition switch is in the off position. Check your wiring around your ignition switch and make sure that everything is clean and neat and wired properly. If an ignition wire came loose there is a chance that the bus may have started but won"t restart. Just one guess of many.
Please keep up this post and let us know what you find out. Also - Putting a (first) name in either your signature, profile or at the end of your post will make us feel like we are helping a real person and not a robot :)
Thanks.
-Sean
Sean-Good point...my name is Dave - I lack the consistency of a robot. LOL
Secondly-Wired properly...part of the bus was converted to 12vthe (headlights for sure)...I have been trackingon dien misc electeical issues. Not sure about the ignition switch. I have a master switch which controls all 24volt. I know it needs to be on to run the starter. I thought there wasnt electronic ignition ...combustion by compression?
I will certainly update this post with the resolution. Hopefully something embarrasingly easy.
it is frustrating to read all about someone else with the same symptom only to find the post abandoned.
-Dave
Dave; only a few things will shut your non electronic engine down. The two main is lack of fuel and lack of air. You are working on fuel issue. Don't assume because your fuel gauge( if you have one )says you have fuel that you do. That has fooled many! Also the tanks are almost 8 ft wide so if your tank is low and your bus is tilted (low) to the drivers side 4 inches can equal 10 gal of fuel. I reread post I doubt if you just moving your fuel lines would have anything to do with it. Bob
Just go buy a cheap electric pump from Auto Zone,buy 5 gals of fuel unscrew the plug in top of the filter base add a fitting in that spot put a hose on both ends 1 for the suction side 1 for the filter run the pump for a few minutes fire that puppy
fwiw the fuel is not wasted it will return to the tank while pumping
good luck
If it don't prime up get back to us. Most everyone has a prime rig set up.
Disnow, my 73 mci MC 7 has 12v headlights from the factory. Wont help getting her started but one less thing to worry about.
John M.
Make sure it's passing the smoke test (passing may not be the correct term...) If it's cranking and there is a lot of white smoke, it's a lack of air issue. If it's cranking and there is little to no white smoke, it's a lack of fuel issue.
Brian
The 2 stroke will blow plenty of white smoke without a solid stream of fuel when cool and never fire a lick he says he is not getting as much white smoke as normal, prime it and get it over with
good luck
Ill hookup one if those prime rigs monday am. Thanks for the tip. Is there a certain psi i should look for in a pump? Heard sonewhere to go with low psi or you may blow out sone seal or sonething?
I assume were talking about the plug on top if the primary fikter.
Starts and runs, stops after air builds up, filters full! Not to question your diagnosis but is it possible you misread the fuel shutoff position?
A classic case of the engine run switch off. Been there. Maybe one of the switches failed?
If the prime is lost it won't start in the first place - been there.
I think this filter and prime stuff is a wild goose chase!
Please let us know what you find out.
Thank you Gus - that was my thought too.
Sure they will start and run with a lost prime if the system was full to start with haven't you guys ever shut the fuel off to one it will run for a minute or 2 at idle with no fuel supply.
If the switch was the problem he would be getting no smoke with the stop engaged and he says he getting white smoke unless I read it wrong
Gus- it started and ran only once...ran about 3 minutes, died and hasnt fired since. I looked directly at the solenoid and lever it contacts to verify it didnt shut itself off by stopping fuel. Bear in mind it would have hit the fast idle solenoid-using more fuel as it aoproached 30psi.
it cranks over nicely but doesnt fire at all.
Is it worthwhile to hookup the external motor and prime it. A lost prime seems logical to me according to symptoms. And the lack of white smoke seems to strenghten the no fuel theory.
I appreciate all the feedback. I have all day tomorrow to get after this issue.
Please correct me if i am wrong or going in the wrong direction. I am a rookie. This isis my first bus and this isis my first few month s on the road with it.
Hang in there Dave, and best of luck!
We were all newbies once ;) ;) ;D
Van
I forgot to mention it has no fuel gauge so i dipstick the fuel. I dont think i have had it less than a half tank. When this happened (now) it is at 3/4 full.
Dave, I think you said you have an MCI 7 and I'm not sure if this applies to you but on most non electronic MCI 9's we have an emergency shutdown that is basically a "flapper" to prevent your engine from getting the air it needs for combustion in the rare case of a runaway engine. If you have it you may have bumped it and it could be shut. It is spring loaded (think mousetrap here) mounted on the air horn on top of the blower and can be reset easily. Just a thought.
Rick
Rick-been there done that -the black smoke like crazy. One of the first things i checked.
Heres a pic of my fuel prime rig. Can i tape (teflon
tape) the brass to brass fittings?
(https://pbs.twimg.com/media/A2_8-R1CUAA_O-q.jpg)
Look right? Valve installed on top entry of primary filter
-dave
Wooooo down the road i went.
Pouring rain here in central Wicsonsin today...of course
Filled and replaced the primary fikter.
Setup that pictured prime rig to the top inlet of the primary filter
Discovered and used yellow diesel appropriate pipe fitting tape. Stayed away from the last few threads.
Ran prime rig for 2 minutes or so
started right up
PO said he hasnt had thia issue before. And that the genset is pipped directly to tank...not tee'd
Ill probably cleanup the install and leave it permanent. Just in case.
Thanks to all you guys/gals?
Victory video below
https://www.youtube.com/watch?v=FINRdFSnFTI&feature=youtube_gdata_player (https://www.youtube.com/watch?v=FINRdFSnFTI&feature=youtube_gdata_player)
He caught that goose Gus and didn't have to chase it far, like others said if they have air and fuel they run maybe not perfect but they will run,glad it worked out for you some DD can be a PITA to prime
good luck
Good news, nothing like the sweet sound of a purring DD!
A few things still puzzle me; you said nothing about the secondary filter - was it full also? If so it is a mystery to me why it wouldn't start? I never did understand why you worked on the primary filter only?
The goose may not be caught yet because I read nothing about what caused the loss of prime. If the cause isn't known what is to keep it from happening again? Could there be a leak between the primary and pump suction side which will pull air in. A leak after the pump will show raw diesel but an air leak before will show nothing.
When priming through the primary filter does this also fill the secondary? If so, where does the air in the secondary go? Will using your primer pump at the secondary work just as well - better? I plan to install a prime connection but had planned to connect it at the secondary. Am I better off to do it at the primary?
When I lost prime on the 4104 it was the check valve at the primary filter which caused the primary to empty. It was a while ago so I don't remember if the secondary emptied also but I think it didn't.
Thread tape makes me nervous. I use teflon paste in a tube on all thread connections so I don't have to worry about those sneaky little slivers of tape getting into any system.
Sorry if i didnt mention the secondary. It spun off and was full. Primary was so difficult to remove...it was an event.
So both filters were full.
According to my interpretation of the pic below the trapped air would end up in the tank after chasing it with fuel through the diagram. Installing the pump at the primary fikter (fuel strainer as diagramed) seemed to be an effectve location.
(https://pbs.twimg.com/media/A3L5Yl4CQAAHr1Z.jpg)
Saw mixed reviews of both paste and tape. So i flipped a coin.
As to the "goose" still havent caught it. Not sure why it lost prime. PO confirmed that hadbt happened to him. He had the bus from 1991 to 2011. Have nt had the same issue yet. Getting it to the mechanic next week.
Thanks. I'm convinced, I'll put mine on the primary also.
Now that I think more about my last post, if there was a leak from the primary to the fuel pump it would have shown up when you pressurized it with the primer pump.
Just a thought but seems to me there was a string here a while ago that said a leaking return line would empty the return line and cause a loss of prime. Not sure I really understand that but it may be something for you to research.
Maybe an emptying return line empties the injector lines?? Seems to me that happened on my Dodge Cummins PU but not sure now which line was leaking since it was a long time ago.
The good thing about paste is there will never any of those nasty little shreds. However, I can see that using way too much paste could cause problems, but that seems to be a common sense thing.
Last December i changed my fuel filters before heading south to Arcadia. I lost prime at the house and refilled and fired her up. Got off the island and headed into NJ and about 80 miles from the house, i turned off 80 onto 287 south and i felt her lose power momentarily and as i came around the ramp she died and i pulled over into the most perfect spot, off the road in a median of sorts. I reprimed the filters and she ran and shut off. did this about 4 times and it was cold and losing daylight. I have no idea what finally made her run but never a problem that day and the next, all the way to fla to my sisters in Ocala. Next morning she had lost prime, and the same thing happened pulling into Arcadia. I would reprime and it seemed fine for awhile but at Arcadia it got worse. I think it was shut off valve installed to make changing the filters easier. It was leaking or sucking air at the handle packing. This stuff will drive you NUTS lol. Have fun with your bus
I have put about 600 miles on over the last few days overnights and a good number of stops. Hasnt lost prime again.
I installed the shutoff valve so that the handle faces down when closed...hoping gravity will help keep it closed. Probably going to add sone kind of safety to hold it closed. Dont want fuel dumping while driving.
Thanks again for all of the help from everyone.
A very small air leak won't show up with daily driving, it usually shows up after sitting awhile.
Don't understand how a shutoff valve could make changing filters easier??
Gus some buses like MCI have the filters lower than the tank they just keep siphoning when you remove the filter so people install a valve to stop the flow
Thanks, I learn something new every day on this board!!