Archived Part 3--Really, Really Hard Starting

[WileyCoyote]

Some of you helped me on earlier threads for the hard starting hot or cold problem on my 2001 HO 6 speed. After the truck sits for 30 minutes or more, it is really hard to start. Only after several cycles of the lift pump with cranking does it start.



Once started, it runs fine. Good as new.



It acts just like the VP44 has drained and is out of fuel.



In fact, I am now convinced that the supply line is indeed draining. If you fill the tank or with a mostly full tank park downhill, the truck is much much easier to start. In fact with a newly topped off tank, it starts normally most of the time. As fuel is consumed, the starting gradually becomes more difficult.



My question is about one way valves in the supply line to the lift pump. On Fords)I have worked on, there is sometimes a rubber one way valve made from latex like rubber tubing or something similar to prevent fuel draining back to the tank. These valves look like a flattened piece of tubing with the flat towards the engine to permit flow only out of the tank, not back in.



Is there a similar valve on the 2500 fuel system? If there is, I would expect it to be in the fuel tank.



Please anyone familiar with the fuel system plumbing for the 01's help!



Thanks,



Harry

 

[pnwradar]

I have pretty much the same problem with my truck. If the truck sits for an hour or more on level ground, it takes 1-2 seconds to start. If I bump the starter and let the lift pump run, it starts right away. If I park nose downhill, it also starts just fine.



I figure I have a leak somewhere in the fuel system, and the injection pump is losing prime. I've also noticed fuel spots underneath when I park on pavement, which makes me think it's a slow leak somewhere between the lift pump and the injection pump.



-jon-

Originally posted by WileyCoyote

Some of you helped me on earlier threads for the hard starting hot or cold problem on my 2001 HO 6 speed. After the truck sits for 30 minutes or more, it is really hard to start. Only after several cycles of the lift pump with cranking does it start.



Once started, it runs fine. Good as new.



It acts just like the VP44 has drained and is out of fuel.



In fact, I am now convinced that the supply line is indeed draining. If you fill the tank or with a mostly full tank park downhill, the truck is much much easier to start. In fact with a newly topped off tank, it starts normally most of the time. As fuel is consumed, the starting gradually becomes more difficult.

 

[MidwestMotorman]

hard starting

I've also noticed fuel spots underneath when I park on pavement

That source should be easy to find. Better do it before you have a huge mess under the hood, and before your suspension and body bushings are permanently damaged.



As far as WileyCoyote's problem, if you have any leak, you will lose prime to filter. The fuel tank develops vacuum. You should hear it when you drive a ways and then shut off the truck. There is a valve that will hiss or whistle very softly in the top of the tank at the fuel sending unit. This hissing is a clue that all is working well. Warm fuel that has cooled can also put a vacuum condition in the tank. This vacuum will pull fuel back into the tank from the source back. I suspect you may have a leaky banjo bolt washer or a loose connection on the pre-lift pump side. You could also have a leak from the fuel canister drain valve or a bad Shrader valve.



Look for ANY signs of fuel. There should be none. Any small amount is clue to a problem. I think the 01's use a Schrader valve in the fuel pressure test ports. Those can and will leak like tire valves leak in the valve stem. They may not leak under pressure, but can leak under vacuum condition. Listen for that vacuum hiss by your fuel tank to be sure that your tank is properly venting. Failure to vent will surely result in a world of problems.



Have you checked your fuel pressure? How about fuel volume? Harder starting as the fuel level is lowered can signal a problem with the lift pump. Check the fuel filter and in the bottom of the housing for any signs of metal or for the dreaded slime. You can disconnect a line and put a jug under it to check the pump output. You can also just turn on the key with the fuel filter out and watch the flow into the housing. Be careful so nothing gets a fuel bath. You might want a friend to help you.



If your VP44 is going bad, you may not know it. Good ones will suck about 3 inches of vacuum at it idle when the lift pump is dead or disabled. A good fuel pressure/vacuum gauge can tell you wonders about your fuel system. If the lift pump is not working as it should, your VP44 may not get the fuel it needs. I do not believe the system has an anti drainback valve other than the VP44. If you crack open the fuel system before the VP44, you should lose everything in the lines. The only fuel present would be in the fuel filter canister.



If one is careful, you can slowly apply slight (a few psi) air pressure through the fuel filler neck. Hold a rag around an air gun to help cover the filler neck, and give it a very light pressure or set the air pressure down. This will supply light pressure to the system and you may soap some fittings and see if you see a leak. Four eyes here are better than two. This should work on anything up to the lift pump. Anything after the lift pump should see 14 psi of fuel pressure and should have leaked before using air. Remember, go as low a psi as you can. You do NOT want to blow hoses, fittings, fuel sender ring seal, or anything else. Please do not attempt if you feel uncomfortable or are not willing to live with the consequences of using too much pressure.



Sorry for the long post. I do not know what other advice you have received, but hopefully I have helped.

 

[Missouri Mule]

WileyCoyote,

It seems to me a member (I think illflem) had a problem with there pickup tube. It had developed a hole and if fuel level was below this hole truck was hard to start but if fuel level was above hole truck started and ran fine.

 

[Steve Campbell]

I did not see parts one and two...

Could this be a missing Banjo washer or one that is no good?



If you have been down that road already, sorry for the post!!!

 

[GLEE]

HARD STARTING

I CAN'T BE SURE YOU HAVE THE SAME 3/8 FUEL HOSE, ABOUT SIX INCHES LONG, THAT ACT AS A FLEX JOINT, AND UNLESS CHANGED, GET DRY ROT AND CRACK, ALLOWING AIR TO ENTER THE SUPPLY LINE, AND THE FUEL DRAINS BACK TO THE TANK. THIS DROVE ME NUTS,TRYING TO FIND THE PROBLEM, AND WHAT WAS WORSE, AS IT OCCURED DURING THE WINTER, WHEN IT WAS PLUGGED INTO THE BLOCK HEATER, IT WOULD START, AFTER AN HOUR UNPLUGGED, IT WOULD TAKE TWO OR THRE MINUTES TO START. --REMEDY-A FRIEND AT CUMMINS NORTH--ONE FOOT OF 3/8' FUEL HOSE, NO PROBLEMS IN OVER A YEAR!! TOTAL COST $1. 26!!!!!!! ONE OTHER THING, THE RETURN FUEL HOSE WOULD HAVE A CONSTANT LEAK, CAUSING THE TRUCK UNDERBODY TO HAVE HAVE FUEL EVERYWHERE, AND FUEL ECONOMY TO NOSEDIVE, AND SHOW UP A LOT EASIER!!! I AM GOING TO CHANGE BOTH LINES AGAIN NEXT FALL,AS I DID LAST YEAR, PREVENTATIVE MAINTENANCE THAT'S INEXPENSIVE!!!!

 

[wcjp]

I don't know if I mentioned this in Parts I or II. Replace your lift pump hose. On my 12V the preheater to lift pump hose was causing a very similar condition to what you're describing. I also replaced the supply/return lines with Diesel Marine hose. Very heavy duty stuff when compared to Oem.

 

[kaffine krazed]

Hook up a fuel pressure gauge. Do you get fuel pressure while cranking before it starts or does the pressure slowly build and once you have pressure the truck starts? Also if you have a fuel pressure guage with a bleed off line you can check for air in the fuel. Hook the pressure gauge up and bump the starter to have the lift pump run and bleed the fuel you will have some air from hooking up the guage but if you continously have air in the fuel be bleed off then air if getting in somewhere. Another check is you have an adapter to hook up to the quik disconnect fitting at the lift pump it to put some clear plastic tubing between the lift pump and the supply line to see if air is getting in somewhere on the suction side of the lift pump. I don't know if anyone else has mentioned this but it could be a bad VP-44.

 

[JTBMC]

When my VP-44 went out the symptoms where similar to yours. Mine (VP) had an internal leak, I could bleed the system anb fire right up, sit for 30 mins or so and it would not start. My pump was leaking out of the top cover just under the TPPS, remove the TPPS lay it out of the way, if you see or smell diesel get the star driver and tighten them up. The leak was very slight and almost unnoticable untill I had my wife start the engine while I held the TPPS in hand and I then could see the fuel leaking out of the gasket under the cover. All of the screws were loose on mine, I tightened the screws and I ran and started good again untill the new pump came in under warrenty. This may not be your problem but its easy enough to check out.

TJ