Losing Prime

[RHARVEY]

Hi Guys,
During our visit in Arkansas I have been parking the truck on a 8% hill(front uphill).
When I start the truck in the morning, it runs about 30 seconds and then dies! I let it roll down on a flat spot and then after a few cranks it fires off, then runs like there is air in the system for a minute or so. When the missing and the smoke stops, she runs normal. This has happened twice, so I decided to do a little test. I parked the truck front down hill overnight to see what would happen. The next morning it started and ran just fine. Each time the truck sits overnight. Some how I am losing prime when the truck is parked up hill.
Whats up!!!!

Rick

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RICK
97 2500,CC,5 SPEED, 3. 54 Limited Slip,Psychotty System,K&N, Pre-Turbo ISSPRO 3" Pyrometer & Boost Guage,Silencer Ring Removed
15,000 RBW 5th Wheel Hitch,25' Excel 5th Wheel,Rancho RSX17000 Shocks,Amsoil Dealer,Straight Piped

 

[illflem]

To get air in the system when shut down you will usually also leak diesel while running. Look for the wet spot, return line or fuel filter area.

 

[RHARVEY]

I've checked the lines on the engine side and found nothing! Nothing that I would think would cause a problem. I check for drips and found nothing. What is strange is that when I park uphill the problem shows up but when I park down hill, it starts and runs great. .

Rick

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RICK
97 2500,CC,5 SPEED, 3. 54 Limited Slip,Psychotty System,K&N, Pre-Turbo ISSPRO 3" Pyrometer & Boost Guage,Silencer Ring Removed
15,000 RBW 5th Wheel Hitch,25' Excel 5th Wheel,Rancho RSX17000 Shocks,Amsoil Dealer,Straight Piped

 

[RAMalama]

RHARVEY -
Check your fuel supply line. My truck did this exact thing. It didn't drop fuel to the ground till it got real bad. My take is your rubber fuel supply line is cracked and allowing air in, this in turn allows the fuel to gravity drain into the tank. Hence no fuel on the ground. Yours is a 12V right?

Parked overnight, the morning start up takes a lot of cranking? Only as long as you've owned the truck (until now) it has never cranked more than one revolution it's whole life?

Bear in mind while the supply line is on the drivers side of the engine it is VERY hard to locate and work on. I recommend cutting the hose clamps with side cutters and pull the line off vice using a screwdriver and trying to undo them. The return line is next to the supply line but the supply line will be wet. When I had mine out it looked fine, then I'd bend it and it looked like an english muffin! It was amazing how bad it was. All the aging was near each end where it would bend to the metal fuel lines at the engine and on the frame.

GOOD LUCK

Ian.

PS: Oh yeah, stay alert for a hot fuel smell while driving coming through your vents. (I let my problem go pretty long but it was easy to diagnose!)

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'95 2WD 3500 std cab, 4:10, 5spd. 68K miles all towing 35ft 14K-lbs triple slide 5er. Completely stock but learning...

[This message has been edited by RAMalama (edited 05-12-2001). ]

[This message has been edited by RAMalama (edited 05-12-2001). ]

[This message has been edited by RAMalama (edited 05-12-2001). ]

 

[Missouri Mule]

Rick,
I also had similar problem for about six months. I would get under the truck looking for leak on rubber hoses at idle and after a fast run never saw it leaking, but had tell tale signs on top starter and actually found fuel inside cap of terminal cable from battery. Had seen what looked like moist area on head next to return line. I changed both supply/return lines. (After determining not fuel return valve. )
Until you get it fixed use primer button to bring fuel pressure up enough to have reasonable easy start.
If you use primer you should be able to hear return fuel valve allow fuel go thru it(has very distinct sound).
If you hear sound return fuel valve is Ok ( at least 30 pushes)
The lift pump(check valves could go bad), return fuel valve and of course the number one cause fuel lines can cause same symptons and same remedies ( park up hill- no start, flat or down hill starts fine).
Good Luck

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Bill Thomas
Missouri Mule - 96 Wht 4X4 ST CC,5 spd, 3. 54, 8 ft bed, 1 ft high cheater boards.
99 Freightliner bl/wht FL60 ISB-5. 9 24v,215 hp,520 tq,6 spd, 3. 59 nsr,16 ft box, 19. 5 tires,Wt/gvw 11,000/23000

 

[RHARVEY]

For what you are telling me, I have 3 things to look for. One would be the lines,two would be the fuel return valve and also the lift pump.
I can start with the lines which was replaced about 10,000 miles ago. And until I parked the truck up hill I found the problem. I can look for leaks, but for other 2 problems, how can I test them to determine for sure?

Rick

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RICK
97 2500,CC,5 SPEED, 3. 54 Limited Slip,Psychotty System,K&N, Pre-Turbo ISSPRO 3" Pyrometer & Boost Guage,Silencer Ring Removed
15,000 RBW 5th Wheel Hitch,25' Excel 5th Wheel,Rancho RSX17000 Shocks,Amsoil Dealer,Straight Piped

 

[Missouri Mule]

Rick,
On the return valve two test, one which I happened to notice while priming the system so truck would start easier (first attempt at starting failed-facing up hill) is that I could tell that the return valve was allowing fuel to go thru it but only when fuel pressure had built up enough (when engine is running you can not hear because of the noise or conitnued operation of valve).
With the primer button being pressed in/out(at least 30 times maybe more) the valve open and closes as to much fuel pressure is asserted against it. The noise told me the valve was working. No noise valve is letting fuel go thru all the time.
Second way is fuel pressure test. While pressure gauge is hooked up and engine is running reach under with your hand (or pliers in hand) and squeeze the rubber return line. If fuel pressure rises your return fuel valve is bad if your pressure doesn't rise bad lift pump ( I don't know if pressure test will pin point bad check valve in lift pummp).
Also check fuel drain where it screws into fuel filter.
Worst scenario injector pump is bad. But I think it is less costly solution. The metal lines where they connect to rubber have developed holes(just another possibilty).

Remeber I never saw a leak- no fuel on ground no fuel dripping- just some moisture(wet looking) around head where fuel line is close by and top starter looked like something was spilling on it(I wiped it clean to verify).
If you or dealer put on same rubber fuel line hose on it, could of cracked again in short time.
Good luck hope problem is solved quickly.

 

[Missouri Mule]

Just thought of way to check lift pump check valve maybe.
Drain fuel heater and pre filter.
Take off big hose between heater and fuel pump. This is my deduction(reasoning) and it could be wrong. If the check valves are OK no fuel will come out of when hose is taken off (maybe a few drops) if they are bad then fuel from in pump and fuel line going to filter will run out of fuel pump intake.
But then again there are three check valves in there(the lift pump).

 

['956Wheel]

Pull the fuel drain valve, (banjo fitting bolt front engine side of the P7100 pump), and check for a broken spring. Mine had the same type problems, get in touch with Piers he has them for 1/2 the cost of Cummins. I got the thing from Cummins... did not know about Piers and his price.

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9535hundred

 

[LarryB]

Yea, this problem an be a real pain in the a$$. Problem being that the leakdown can be so small that it is vurtually undetectable. Since air is thinner than fuel, air can be drawn through the sides of a bad fuel hose without fuel being able to leak out because its too thick. It won't even show as moisture.

It sounds like air to me and in order for air to get in I would think it must be a bad hose. I personally have never had a problem of a bad check valve letting in air.

Another $. 02 from me.
Larry

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1972 Chinook class C with 96/215 5spd, 4/5" exh, 4"BD, MagHytec, 85gal fuel, K&N RE0880, AutoMeter, 370's, BD gov kit, BD afc kit, 16cm, 16%btdc, yada-yada-yada
www.fostertruck.com/cummins

 

[illflem]

Besides the hoses the other suspect leak areas are the fuel filter gaskets, the bleed screw or the water drain valve. Have you noticed what your fuel level is when the problem occurs parked up hill? I had a pinhole leak in the pickup tube inside the tank module that only sucked air when the tank was below 1/2, took a long time to figure that one out. If your truck has no starting problems with a full tank parked up hill it may be another place to look. The pickup tube moves inside the module and can get a hole rubbed in it from the side of the case. This is rare,but does happen.

 

[RHARVEY]

I called Cummins and described the problem, and the customer rep. didn't hestitate. . he said that there was a bad valve in the lift pump! I ask the questions of how it acted in different ways and it was exactly the way it is doing.
So as it stands now,,she will get a new lift pump or what the book calls a transfer pump.
I will keep you posted on what happens. .

Rick

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RICK
97 2500,CC,5 SPEED, 3. 54 Limited Slip,Psychotty System,K&N, Pre-Turbo ISSPRO 3" Pyrometer & Boost Guage,Silencer Ring Removed
15,000 RBW 5th Wheel Hitch,25' Excel 5th Wheel,Rancho RSX17000 Shocks,Amsoil Dealer,Straight Piped

 

[Missouri Mule]

The symptoms Rick is having could be air getting into fuel system.
But if you recall the TSB on overflow valve (fuel return valve) in issue 14, if bad it could cause hard to start and poor running condition and it wasn't letting air into system. Just letting enough fuel to drain back to tank so it would be hard to start.

My first hard start problem was around 20,000 under warranty Dodge/Cummins replaced the P7100 Injector pump. There was a leak at overflow valve.
Second time over 100,000 miles ended up being fuel hoses.
The symptoms are a about the same for several components of the fuel system.
Leaking fuel lines
Leaking fuel filter gasket
Leaking O-ring on drain valve
Leaking Drain valve
Bad overflow valve
Lift(transfer) pump,check valves or leaking casing
Injector pump

If your check valve(s) are bad, during engine operation and your taking fuel pressure test will they cause fluctuating pressure readings?

Rick what was the symptom that pin pointed the transfer pump and not another component of fuel system?

 

[RHARVEY]

Hi Guys,

The problem has been solved! The lift pump has been replaced... . I parked the truck on the hill last night and started it this morning with NO problems. . It runs great with no missing. .

I had the mech. check all the hoses and all fuel lines and he found no problems what so ever.
Thanks for all the responses. .
If your ever in the state of Arkansas and need work done,,check out Mid-South Cummins in Little Rock. . they do a great job. .

Rick

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RICK
97 2500,CC,5 SPEED, 3. 54 Limited Slip,Psychotty System,K&N, Pre-Turbo ISSPRO 3" Pyrometer & Boost Guage,Silencer Ring Removed
15,000 RBW 5th Wheel Hitch,25' Excel 5th Wheel,Rancho RSX17000 Shocks,Amsoil Dealer,Straight Piped

 

[RHARVEY]

Back to the prime problem... . As you can see by the dates on the post, I had the problem with losing prime back in May. I went to start her yesterday, and it started just fine but after a few seconds of running, it starved out and died. After some effort it started back up, coughed for a while and leveled out and ran fine

This morning I went out to start her and before I did I hit the prime pump a few times just to see the if I could hear the return valve working which it did . Hit the started and she fired right up with no problems.

Now this is a head scratcher... Any ideas...



Thanks

Rick

 

[illflem]

Rick,since replacing the lift pump cured it the first time that's where I'd start again. I've had several replacement mechanical fuel pumps on different brands of engines (never Cummins) go out faster than they should have even when OEM. I know that if you let a fuel pump go too long making a ticking sound that the cam lobe that drives the pump can get damaged and will take out new pumps faster. I hope this isn't the case with yours and you just got a bad pump. Also go back to an air leak check again.