Engine/Transmission (1994 - 1998) Wierd Hard Start

[JoshPeters]

Wierd Hard Star

I have a 96 3500 with the 12valve. Occasionally when it's below approx 45degrees in the morning and the truck has sat for more than 4 hours, it starts, runs for about 30-35 seconds and dies. Then it cranks (foot on the floor) for about 20 seconds, catches one cylinder... then multiple... and runs fine. I have a fairly steep driveway. This has happened before, so I started parking nose down hill and it didn't happen. Last night it was 63 degrees when I parked the truck at 7:50pm, I started the truck this AM at 5:45, and it was 41 degrees. The nose was uphill. It has never happened at work where it sits in a flat parking lot or when I have had the nose parked downhill. Do I have a check valve going bad somewhere? Where? Has anyone had this happen before? It's not the end of the world, just a PITA.



Josh

 

[Joe G.]

Have you replaced the supply and return fuel hoses? That may be the problem. If it is, then the problem will just get worse.

 

[JoshPeters]

I haven't replaced those. I'm just wondering if it's a check valve, due to the inclination issue.



Josh

 

[Joe G.]

Might be, but I would not think the check valve would act like that. Do you have any idea what your fuel pressure is?

 

[redram]

I agree with Joe (see Joe, we can agree on somethings and by the way, I'm still using ELC Coolant and haven't had a lick of problems)



The incline might be causing a syphon effect with the nose higher that does not occur with the nose lower. Level ground is neutral in this case.



With the nose higher, and the return / supply rubber hoses cracking, it may be allowing the fuel to return to the fuel tank as air slowly seeps through the fine cracks in the rubber lines as these lines are higher than the fuel tank with the nose elevated.



With the nose down, the tank is the same or higher than the fuel lines at the back of the enigne.



Geez, 41 degrees - it's 90+ in Texas!

31 degree incline is very steep for a driveway. Anything over 20 degrees is fairly steep. I would imagine that running low on fuel and parking on that steep a slope might also cause problems - as in fuel pickup problems as the flow flows away from the centrally located pickup tube.

 

[JoshPeters]

What exactly should I get for fuel supply/return lines?



It's about 60 for the day time high right now, and has been great sleepin weather at about 40 at night. The coolist it has been at night lately has been about 30-32. We had frost warnings last night for a few areas.



Josh

PS, 90 is to dang hot!

 

[illflem]

A couple of other folks here have reported the same uphill/downhill problem when the check valves in the lift pump are shot. Unfortunately you have to buy the entire lift pump to replace them.



If you haven't replaced at least the return hose it's just a matter of time, but a leak in it usually results in hard starting after an overnight or longer sit no matter which way you're parked.



You will need about two feet of 5/16'' diesel rated hose, a couple of clamps and a lot of patience, it's a tight fit. In the picture below you can see the line where it passes under the water temp sensor (upper right) the end with the clamp is to the left of the filter, which needs to be removed to gain access. If you have vacuum assisted brakes you will also need to remove the two nuts that hold the master cylinder with fluid reservoir and move it towards the drivers side, pull the large vacuum hose off the brake booster and it moves easier than it looks.

To get to the other end of the hose you need to move the two relays with their bracket out of the way, one 3/8'' screw under the hood seal does it. Remove the hose hold down clamps towards the rear of the filter. I also completely remove the engine lift hook. Now you can follow the hose down by feel and remove the clamp. The rest with the new hose is self evident. The intake line is 3/8'' in the same area but a little easier to get at. Sure wish it was as easy to see as this picture.



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[JohnE]

After seeing this first hand I believe you should do the return hose and overflow valve. If it continues, then attack the lift pump area as in fuel strainer/heater and lift pump.

It just may be a lift pump, but it never hurts doing the overflow & return line anyway.



nice headlights, too.



-John

 

[ChillyDog]

Josh,



Let me know when/if you do the return line. I would like to do mine to. I have a fuel pressure adapter, so if you want to check your fuel pressure sometime we can do that to.



Bill