traleblayzer

Hi guys,

My 94 has been a little rough starting for a few days. It would take a few extra cranks to get going, and it would shudder a little when it did start. Then it would be fine and drive well. Today, after sitting a day, it won't start. It turns over strong, and seems to catch a cylinder or two now and then, but too weakly to catch. It feels like its not getting enough fuel. It's got dual tanks and its been having the crossover issue as of the past few weeks if that is relevant. I need any help I can get, as I'm used to carburetors and my FI experience is limited.

Here are stats:
94 f150 supercab 4wd
351
Dual tanks
95k miles
Auto trans

Thanks a lot for any suggestions.
Tom

jbriggs

Do you have good spark? Might want to check your fual filter, or it could be your fuel pump (****ty thing is they are in the gas tank)

traleblayzer

I won't have a chance to check spark until the morning, but I know its getting some spark because of the occasional light kicks. I'm considering the filter, but would that not also affect driving at speed? It seems to be fine at speed and warm restart, only seems to have trouble at cold start.

Thanks!
Tom

jbriggs

You might want to do a good tune up if you haven't in a while. Change plugs, wires, fuel filter, air filter. Then you cover the basics for an engine to run; fuel, air and spark.

traleblayzer

Thanks, I was thinking along the same lines once I can start testing things tomorrow.

Also, I forgot to mention that when I turn the key I can hear the fuel pumps prime in either tank, so I know they're getting power.

jbriggs

Well good luck. Hope its something easy!!

scoby41

I'm having similar problems with my truck. I cleaned my IAC and that actually helped a little. When I took my throttle body off to clean as well, my intake manifold is full of gunk so I know that's something that needs to be addressed. Wouldn't hurt to do a quick reset too.

traleblayzer

Well it's definitely getting spark, so it must be a fuel problem. I'm going to grab some starting fluid and see if it will run if I give it a little kick. I'll try to rent a fuel pressure tester too. If it does turn out to only be a problem starting, and will run after a shot of starter fluid, any ideas? In the carburetor world I'd check the idle circuits, or the choke, but I'm at a loss when it comes to FI.

Thanks!

ymeski56

Need fuel pressure at the fuel rail for both tanks when selected.

traleblayzer

So I got it to start, with a little starting fluid and cranking it for a while to let the small kicks build up momentum. I did some testing on the fuel pressure:

42 psi engine off (spec 35-45)
32 psi engine running (spec 30-45)

I'm a little worried about that engine running pressure being so close to the bottom of the spec. I'm thinking I should change the fuel filter, in case it's restricting flow, but it's going to take a while to get behind the fuel tank and skid plate to the filter. I suppose it could be the fuel pressure regulator, but it's not really out of spec. I put in a bottle of Sea Foam that I had laying around, and drove for a while at highway speed with overdrive off to run some extra fuel/sea foam through for a while. Its running fine, power at speed is fine, and it seems to restart while hot just fine. However I'm still worried about the cold start, so I'll let it sit and try again, and let you guys know what happens.

Do you guys think I might have just got a bad tank of gas? I ended up in a situation where I had to run the tank really low to get to the next station about a week back, I'm thinking it might have sucked up some junk. Or, could it be the regulator or the IAC? If I understand it right, the IAC works like the choke on a carb, and this cold start issue feels a lot like trying to cold start a carb engine without the choke set.

Thanks for the tips everybody
-Tom