I have followed the fuel lines and they seem to all go to different places on the engine? I have 6 separate fuel lines and they seem to all come from the primary and secondary fuel filters and straight to different places on my engine?
It's buried up under the coolant crossover just to the left of that lifting bracket. Has 2 lines going to the 90 degree fittings.
Bob
Quote from: wildbob24 on December 19, 2014, 09:17:40 AM
It's buried up under the coolant crossover just to the left of that lifting bracket. Has 2 lines going to the 90 degree fittings.
Bob
Is one line a incoming and the other a outgoing? How can I test to see if it is working? Can I simply take one of the lines off and see if fuel comes out when I crank the engine?
Scott, tell us what you are trying to accomplish.
GaryD
I think he has a shut problem Gary it runs till it get a little air build up then shuts off like no fuel or he is not getting a good prime I have to just pickup bits and pieces from his post
Well several weeks ago I started the bus and it ran for a couple minutes and then started to run rough. I shut it off and the next day tried to start it, and it would start and run for about 30 seconds and die. I was told to change the fuel filters and add some fuel in case it had run out of gas. I did all this and it still only starts and runs rough for a short time(sometimes it will run for a minute or 2, and other times it only runs for 30 seconds. When I changed the fuel filters, I found out the 2 spin on filter points are both secondary filter size, so I had to use 2 secondary filters( this is how it was set up and ran fine from Phoenix to St. Louis with no problem). I only added 12 gallons, but am thinking(not sure) that if it ran out of fuel, and I added 12 gallons that should be enough to get it to run ok? My generator runs off the main tank and will start and run fine, and they usually stop running before the bus runs out of fuel, so I'm thinking I have enough fuel, so it must be something else? I'm at a total loss.
Clifford, what is a shut problem, and how can I or what do I check to see if it is the cause?
If you take lines off, take careful note of where they came from. It's real easy to hook them up backwards. Each head has an input and a return output, there is usually a cross-over from the return of one head to the input of the other head and there is a special restrictor fitting on the return output on one of the heads - that one goes back to the fuel tank. I would take off one of the input hoses that goes directly to one of the heads, I wouldn't take the fuel pump fittings off. If I wanted to test to see if it was working (and it won't work without a good prime) I would just put a pressure gauge on the secondary filter. I would crank it and expect to see around 10 psi of fuel pressure at least. If I wanted to make sure it had a good prime beyond all doubt, I'd make me up a little fuel tank with a couple of quarts of fuel in it, hang it up above the engine and jimmy up a connection to the input of the fuel pump (bottom fitting is the inlet) and crank the engine.
Prime it good and leave the priming pump running start it and see if it keeps running it should even if the transfer pump is bad
Ok now I am even more confused. I noticed that there is what looks to be a bolt head underneath the fuel pump that has fuel dripping off it. I removed the bottom or inlet fuel line from the fuel pump and heard a gurgling sound. I tried to start it and it started and ran fine? While running, the inlet line would spit a very small amount of fuel out every 5 seconds, but kept running until I turned it off?
Clifford I tried running the prime pump while starting it and it seemed to make it die faster?
Will it hurt it to start it and let it run for 10 minutes so I can move it 6 inches in my driveway without the inlet fuel line connected?
Well, it's Christmas time so I guess a miracle isn't out of order. For us mortals, how do you think the engine will run with the INLET line to the pump disconnected? Keeping in mind the fuel comes to the pump along the inlet line?
Brian ;D
Scott, any chance you have an air compressor that you could air up your bus before you even start it. That way it is ready to move the minute it fires up.
Mark
I hooked my air compressor up and got it pumped up to 92 psi, and then started my bus up and ran it to get the air pressure up enough to move it( had to take both fuel filters off and fill them 3 times), but finally got it moved. I figured out that the inlet is the top line and not the bottom line on my fuel pump. I figured this out by taking the top line off and fuel came out it while running. While running when the bottom line was off it would spit fuel out a little and constantly put air out it. What could my problem be?
It's kinda hard to figure out what's going on from a 1000 miles away...but were I you I would (after it is running) (with the fuel line unhooked if that's the only way) or with the electric pump working...
I would go to my fuel tank and decipher which is the feed fuel line and which one is the return, then I would loosen or remove the return line and gage the flow at that point.
My suspicion at the moment is that the electric pump may be in backwards.... is there a fuel flow arrow on the pump ? check that.
I also wonder if the fuel restriction fitting on the return fuel line is the correct one....
I also wonder if the fuel hoses are routed correctly thru the filters...but you say that portion is still "intact" from your cross country trip....
Quote from: harleyman_1000 on December 19, 2014, 10:53:53 AM
Ok now I am even more confused. I noticed that there is what looks to be a bolt head underneath the fuel pump that has fuel dripping off it. I removed the bottom or inlet fuel line from the fuel pump and heard a gurgling sound. I tried to start it and it started and ran fine? While running, the inlet line would spit a very small amount of fuel out every 5 seconds, but kept running until I turned it off?
Make sure your electric pump is hooked up correctly as far as power is concerned, some dc motors will run and pump backwards if hooked up wrong
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You do need to minimize the amount of "dry" runs that pump see's....the fuel is the only thing that lubricates the innards of that pump....
Your pump should be sucking fuel out of the filters and feeding to the fuel rail in/at the heads....
That's why I say to get the electric pump going....perhaps move it as close to the tank as possible... then you know it is sucking fuel from the tank...then you can start cracking lines to determine the flows... start at the return at the tank... if it is returning, it should be plumbed correctly.
If it needed re-primed 3 times...it's sucking air some where...
Make sure your electric pump is hooked up correctly as far as power is concerned, some dc motors will run and pump backwards if hooked up wrongWhich is part of why I asked if it was a one wire or two wire pump..
Quote from: harleyman_1000 on December 19, 2014, 02:49:25 PM
I hooked my air compressor up and got it pumped up to 92 psi, and then started my bus up and ran it to get the air pressure up enough to move it( had to take both fuel filters off and fill them 3 times), but finally got it moved. I figured out that the inlet is the top line and not the bottom line on my fuel pump. I figured this out by taking the top line off and fuel came out it while running. While running when the bottom line was off it would spit fuel out a little and constantly put air out it. What could my problem be?
Quote from: eagle19952 on December 19, 2014, 03:06:24 PM
You do need to minimize the amount of "dry" runs that pump see's....the fuel is the only thing that lubricates the innards of that pump....
Your pump should be sucking fuel out of the filters and feeding to the fuel rail in/at the heads....
That's why I say to get the electric pump going....perhaps move it as close to the tank as possible... then you know it is sucking fuel from the tank...then you can start cracking lines to determine the flows... start at the return at the tank... if it is returning, it should be plumbed correctly.
If it needed re-primed 3 times...it's sucking air some where...
Make sure your electric pump is hooked up correctly as far as power is concerned, some dc motors will run and pump backwards if hooked up wrong
Which is part of why I asked if it was a one wire or two wire pump..
I'm assuming you asking about the prime pump?
Prime pump, yes
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Quote from: harleyman_1000 on December 19, 2014, 05:03:28 PM
I'm assuming you asking about the prime pump?
no I am talking about the main engine fuel pump....the drive portion of that pump is engine oil lubed...
the internal gears that move the fuel are lubed by the fuel flowing through it.
why the motor runs with a line off needs to be solved...if in fact I understand what you wrote.
Quote from: eagle19952 on December 19, 2014, 03:06:24 PM
You do need to minimize the amount of "dry" runs that pump see's....the fuel is the only thing that lubricates the innards of that pump....
Your pump should be sucking fuel out of the filters and feeding to the fuel rail in/at the heads....
That's why I say to get the electric pump going....perhaps move it as close to the tank as possible... then you know it is sucking fuel from the tank...then you can start cracking lines to determine the flows... start at the return at the tank... if it is returning, it should be plumbed correctly.
If it needed re-primed 3 times...it's sucking air some where...
Make sure your electric pump is hooked up correctly as far as power is concerned, some dc motors will run and pump backwards if hooked up wrong
There is a total of 3 wires going to the pump 2 blue or green(can't see well with flashlight)going to 1 contact and 1 red wire going to the other contact.
Which is part of why I asked if it was a one wire or two wire pump..
And I was referring to your electric prime pump of course. Hooked one up backwards once, found out they do indeed pump backwards. Easy to check, otherwise sounds like eagle is giving you the best info
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There is a total of 3 wires going to the pump 2 blue or green(can't see well with flashlight)going to 1 contact and 1 red wire going to the other contact.
Which is part of why I asked if it was a one wire or two wire pump..
The 3 wires I'm talking about hook above the engine fuel pump
This probably won't help at all, but here is what I know about my 6V92. The fuel pump will not pull fuel from the tank. The fuel pump will usually not pull fuel from the filters. To get mine primed when I get air in the system I have to crack the supply line at the fuel pump and then prime the system all the way up to the fuel pump. This is the only way that mine will run and stay running with air in the system. I don't have an electric prime pump on that engine so I have primed it by pressurizing the tank with a blow gun on my air hose and a rag to seal it in the filler neck. I am not certain, but it just sounds to me like you have air in the system somewhere.
If a Detroit is plumbed properly and the filters filled and installed properly, there is absolutely no reason to have to re-prime for the life of the filters.
There is bad hoses, loose connections or loose filters. I can not think of any other causes to lose prime.
I have run filters for more than two years before changing on my personal stuff.
And never lost prime. But I am very familiar with how my bus runs and when it is "losing power, when something is not "right"
You folks who have "lost prime" need to really dig in and find out the whys ... it is not normal.
Believe it or not, I knew an old Detroit hand who used shaving cream as a last resort to try and find suction leaks....
and starting fluid to find intake leaks.
How can shaving cream be used to find fuel leaks?
Suction leaks. You can sometimes see the fluffy cream kind of cratering as it gets sucked into the leak. Never tried it (don't use shaving cream) but heard of it. You used to be able to use WD40 to find intake leaks on gas engines, made the engine speed up, but they changed the formulation to be less flammable.
Brian
correct me if I'm wrong but doesn't the fuel flow through the primary filter then the engine fuel pump then the secondary filter and into the injectors and back into the fuel tank
Rick
Yup you are correct I was just to lazy to go into detail what needs to be solved is the why it runs unhooked which I think is a pluming problem for which the electric pump is compensating....
Quote from: Rick 74 MC-8 on December 20, 2014, 10:12:12 AM
correct me if I'm wrong but doesn't the fuel flow through the primary filter then the engine fuel pump then the secondary filter and into the injectors and back into the fuel tank
Rick
On my setup the fuel goes from the primary filter to the secondary filter (actually mine has 2 secondary filters and no primary filter) and then to the engine. I'm not sure if my setup is correct or not, but it was this way when I bought it in phoenix and it was fine coming back to St. Louis. It just started having problems while sitting in my driveway.
Could it be cold enough that the fuel is gelling. Have you put fuel in it since they started mixing or is it still summer fuel?
Rick
It's the same fuel that was in it before last winter, but I treated it then. Do I need to retreat the fuel?