My 91 (150 5.0) apparently hates cold weather like me. Its been starting just fine until this morning (31* outside). It just wanted to crank but not fire. Once it fired, it ran rough as all get out till it started to warm up. It showed a check engine light but when I hooked the reader up, no codes were shown. Any suggestions what to look at?

 

Once it warmed up, did it return to normal?

Did you ever change the temp sending unit to the computer ( the one with 2 wires)
off the heater hose by the thermostat housing like we discussed several years ago?
It may be telling the truck the temp is already at operating temp, and the computer is not making the fuel rich enough to fire it off cold
( think of it as an old school choke)

 

It ran fine once it warmed up.

Yes, I put a new sensor/sending unit in when I replaced the water pump this summer.

 

When is the last time you changed the fuel filter?
Sounds like you may have picked up some water in your gas.
Try a filter change, and some dry gas in both tanks

 

Thanks Charlie, I'll give that a try. I know the filter isn't too old but its worth a try.

 

Did it do it on both tanks?

 

I didn't try it on the other tank. I'll have to wait till I get home tomorrow to try it. I just filled both tanks the other day.

 

Try same tank first, see if problem persists. if so, STOP, and switch tanks, start over.
It may be that there is water in both tanks, may not.
Hopefully not

 

Hey Charlie, sorry it's been a while since I've been on, been crazy busy.

I changed the filter and fuel pump relay yesterday. When the key is turned on, I can hear the pump working. In the front tank, once it's built pressure, it doesn't make any sound. The back tank, it kicks on and off every 10-15 seconds. It still took a little bit to start but not as bad as it was previously. So regardless, its heading in the right direction.

 

Check your lines at the tank for age and cracking. It could be that you have leaks causing pressure loss or air intrusion. 20+ year old lines can do crazy things.

 

Thank you Greywolf, I'll have to check them again.

Like I said earlier, once it starts and gets warmed up a bit, she runs like a charm.

 

Those are high pressure fuel lines, fuel is being pushed from the tank. If there were a problem with the lines, it would be spraying fuel under the truck

Scott, have you added dry gas, or lucus yet, to see if there is a water problem with the fuel in the tank?

 

Ken is correct. I have been chasing my tail with my 'Sploder for 2 months now. I finally took it to a shop for 2nd opinion, and they determined the new temp sender to the computer from NAPA I just replaced is just as bad as the factory one I replaced

 

I've used yellow bottle HEAT successfully several times to rid moisture plaguing problems out of the 72 390 F250, the boat and the cars. Its about the cheapest stuff out there, but for me has seemed to work just as well as some of the more expensive stuff. Put a bottle in every few months just for PM purposes.