another hard start, NOT THE GPS!

[cowboyup95]

Ok I am having the exact same problem on my truck i did some tests and the injectors are losing pressure over night and when you are cranking the engine you are forcing the air out and that is why it is not running right for a while

[J-ROCK]

The injectors are loosing pressure?

[BruceM]

FUEL PRESSURE RELIEF CAP!! I broke mine last year, replaced it with a new one from the dealer (~$40), my truck was taking a hell of a long time to start and I would get the occasional SES light when trying to get her moving fast.

Hooked up a fuel pressure gauge and found that at idle I had 19 psi. I popped the fuel pressure relief cap and line off the side of the fuel bowl and found my FPR spring stuck in the return line. Looks like the new cap I bought failed and the center part broke out allowing the spring to slide into the return to the tank tube. This allows the relief sleeve to open WAYYY up and basically your fuel pump is flowing 90% of the fuel up thru the filter then right back to the tank, where it starts its journey all over :-/

This lack of fuel pressure would be worse when colder since the fuel pump runs slower because of the lower battery voltage from the glow plugs and all that. I now realize why I was having to crank for 1-2 minutes when it dropped to 20's here one morning. When the fuel pump kicks off my pressure dropped to 0 faster than anything.

Ghetto rigged up a piece of coat hanger wire in a "V" shape and wedged it in the cap. Installed it back on the truck and had 45 psi. Opened it back up and put a small screw in the spring and then I had 62psi at cold startup with the glow plugs making my voltage in the truck down around 11.5V (even with dual alts and 2 brand new batteries) Soon as the GP's turn off and the voltage comes up to 14.2-14.3v I have 71psi at idle.

Truck now runs like i remember it did, and my MPG's have gone up, EGT's have gone down, and the fuel pedal is much more responsive.

pop the FPR cap off, it's 2 torx bits, and you need to loosen the vibralok fitting on the pipe to the cap. hit it with some PB first and be very very careful when tightening the vibralok fitting down on the reassembly. I broke the cast aluminum threaded part of the cap with very very light pressure tightening it.

If your FPR spring is gone (as in somewhere in the return line or in the fuel tank) most Ford dealers stock the FPR kit for $50-$60 and it has all the new parts except for the cap. The cap is a seperate parts pack.

I need to find a new seal for the Fuel pressure relief valve part as mine is squashed flat and half worn away. New ones are in the fpr spring kit from ford, but I can't see spending $50+ for a .02 beveled o-ring.

I have a new cap in the package in my truck right now and if anyone needs the part number I can go get it. I'm prolly gonna return it since my ghetto coat hanger thing is working nicely :-)

[wags1992]

How many miles do all these trucks have that are having cold starting problems? How many of these trucks have aftermarket air filters or intakes on them or really dirty stock air filters? I am guessing if your glow plugs are working properly then you probably have low compression. I have seen it many times on the 7.3L. When the engine is cold it has very low compression, but when it gets warm the rings can seat to the cyl walls better and has good compression. I usually see low compression on higher mileage engines and engines that have aftermarket intakes on them(especially the ones that have not been cleaned) Air filters need to be maintained on a 7.3L or it will create problems. I recommend doing a compression test with the engine cold and see your numbers.

[99red7.3]

My truck has around 217xxx miles on it so where and how would i go about getting a compression test . what should my readings be if it has good compression and what would the cost of this be ?

[jokerracing770]

did you replace the harness in the valve covers mine did the same thing i put new harness in and my truck will start everyday

[wags1992]

Originally Posted by 99red7.3

My truck has around 217xxx miles on it so where and how would i go about getting a compression test . what should my readings be if it has good compression and what would the cost of this be ?

I would recommend taking it to a dealer and having them check it out for you. You are looking around $700 to have them do a compression test, you can do it yourself but its not very easy. You have to pull both valve covers and all 8 glow plugs and get a gauge and adaptor that will fit in the glow plug hole then you can do the compression test. As far as what readings are good Ford doesn't have a spec they just want all cyls to be within 75% of each other. I would say a good compression in this instance would be around 200PSI. Thats just a guess and it will be give and take. Id say get your numbers post them and then we can talk about it.

[99red7.3]

Originally Posted by jokerracing770

did you replace the harness in the valve covers mine did the same thing i put new harness in and my truck will start everyday

What do you mean by this ? did you replace just the harness under the valve cover or did you replace them both outside and inside for both sides?

[Quickhorse]

Originally Posted by 99red7.3

What do you mean by this ? did you replace just the harness under the valve cover or did you replace them both outside and inside for both sides?

You can buy just the UVC harness (under valve cover) or you can buy just the valve cover gasket. You can also buy this stuff as a set. Usually though, the harness doesn't go bad it just limps down out of the plug and causes issues. Ford has a shim kit for this problem. $13 per shim and they are the size of a penny. You can also just zip tie them for the cost of 4 zip ties.

[99red7.3]

Originally Posted by Quickhorse

You can buy just the UVC harness (under valve cover) or you can buy just the valve cover gasket. You can also buy this stuff as a set. Usually though, the harness doesn't go bad it just limps down out of the plug and causes issues. Ford has a shim kit for this problem. $13 per shim and they are the size of a penny. You can also just zip tie them for the cost of 4 zip ties.

Oh ok thank you thats good to know but that doesnt seam like thats what my issue is as when my truck gets up to running temperature it runs fine unless some how when it gets warm it helps the plugs get a better conection