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E7 400 Mechanical - Won't start in morning without priming


Davedownunder
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My E7 Valueliner has this issue that it wont start in the morning (or after about a 6 hour rest) without the fuel being primed up. Once the truck is going throughout my work day, it will restart OK. I have been living with this problem for a few months now and have tried many things to overcome this issue.

Initially suspecting there is "air in the system" I have replaced practically all fittings and hoses to eliminate any intake of air.

All hoses have been replaced

All fittings have been replaced

The pressure relief valve has been replaced

The Primary Filter head has been replaced. When I removed the old one I did find 3 fractures in the threads and was excited that this might be the answer - however it proved not to be so and the problem remains.

A new fuel pump has been fitted -

Another suspicious clue is that there appears to be excessive vaporization in the fuel tank. this excessive vapour will be present as soon as the fuel starts returning to the tank from the engine. How much vapour is normal? Is this a related problem to my fuel for starting issue?

I have noticed that the suction line from the tank to the Primary filter is empty and even the Primary filter having about an inch at the top empty on inspection after a period of a few hours. The lines from this filter to the lift pump and then subsequently to the next filter on to the fuel pump are full.

Any Clues

DAVE

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I am no genius in this area and have not had the problem with a mack but, I have had this very issue with a series 60 Detroit. Have you thought about injectors at all? My series 60 was doing the same exact thing. At first it took a few days of sitting unused...... then it got to where it didn't want to start in just a few short hours. The culprit wound up being injectors. I had a size larger installed due to needing them for a hot program in the computer. The starting issue went away and has not came up again. I am certain that sizing them up was not the cure, just the fact that none of them are leaking back while parked and cooled down.

I hope that this helps. I'd be willing to bet that you have one injector that is leaking back after cool down but not bad enough to run poorly.

As to the vapor issue in the tanks. I know nothing.

Good luck

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:chili:Take care of your ride and it will take care of you :chili:

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Try when it is hot pulling the plastic fuel return off of its fitting at the front head while running.Look for compression or vapors with return fuel.If you have any vapors it will be compression leaking by the bottom of the injectors and you will need to pull injctors and ream out th carbon in the head then reseal the injectors.

glenn akers

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Glen

I just tried your suggestion of removing the injector return line and fuel was spurting out of the line comping from the pump end. This was not what I was expecting - now I am totally baffled. :blush:

This is doing my head in - and today in Sydney Australia it is 37 Degrees Celsius (98.6 in your scale) way too hot to be working in the driveway. :pat:

Dave

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That would be normal and I should have told you to put some vise grips on the line so you could watch the return from the return fitting in the head.You will get a little fuel from it.But if much it means the injector line to injector joint is leaking.Vapor means compression.

glenn akers

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Keep it working dave

I don't know if E7 have the cross over tube between the heads the same as E6 but I remember that this was loose on one of mine once and caused the same issue I nipped it up and no further problems let me know how you go

Karl / upright transport

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I put a one way valve in the suction line from the tank before the primary filter yesterday. Hoping this would elevate the "air in the system" possibility - but this morning the problem is just the same. Looking like injector tube not sealing on the injector problem may be the answer. Removed the crossover tube this morning and replaced the 2 grommets (they looked fine but replaced them anyway) Just now awaiting a time period of a few hours to see if it starts. :SMOKIE-RT:

Still need to know the optimum pump timing to ensure this is set correctly.

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OK bad news - the problem is still there. Had to prime it up the last few mornings.

Trying now by rerouting a fuel line to eliminate a potential problem from the line creating a vertical uplift into the pump. Probably not the answer but I am clutching at straws at the moment and it was suggested that the fuel line might be better to have a straight run all downhill to the fuel pump then that setup I had - see photos

Also tonight I have disconnected the return line and placed a container under to see if any fuel is leaking this way. :pat:

post-19717-0-02977400-1422609198_thumb.j

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How long did it work for after tightening cross over tube Dave sometimes they need another nip up ( don't know why but I had one come loose again then nipped up and was good for ever give me a call when you have it sorted we finally have dry weather up here so can get back into carting onto sites again

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The change of position of the fuel line to the pump made no difference at all. There really was only 1 drop of fuel in the container under the pressure relief valve indicating there isn't a leak here.

Back in the shed today for me ........

It was suggested I look at the F.A.S.S Fuel System. I have started another thread on here inquiring of you my fellow trucking compatriots, to get any info on this product. see forum entry in "Engine and Transmission" section titled "FASS Fuel System"

DAVE

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Just a thought….. going by other post ,are the fuel filters originally behind the front tire? If they are, is it possible that the heat of the new location is doing something to the fuel. I can imagine it gets very hot there beside the rad. Could it be possible that the fuel is heating so much, that when it cools at night the filter is a 1/4 empty.

Could be nonsense , just throwing ideas out.

Hope you find your problem.

Keith 

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