Fuel Pump Problems and Extra Cold Temps

[Butch]

We have been having some really cold weather (-20's) in Anchorage the last few days and my 98 D1 is giving me an odd problem. If I live my truck plugged in (oil, tranny and battery heater) over night, when I come out in the morning to start it, it cranks like mad, but it will not turn over. In warmer temps, around 0 degrees, it starts fine.

When I turn the key, I don't hear my fuel pump, but that is normal. I removed the access panel to get to the fuel pump and everything looks fine. I made sure all the wires were pushed on the connectors good and tight. I replaced the fuel pump fuse under the hood and still the same results. My CEL does not come on when the key is in pos 2, but after a good amount of time cranking, it will flash for a second or two and then the truck will start. It only happens in the morning. After it is running, it starts fine for the rest of the day. Could it be the fuel pump going out?

I tried to check the fuel pressure with a regular tire gauge, but that didn't work to well! When I go to the parts store, I am picking up a fuel gauge, dio-electric cleaner/grease and rechecking everything. Sorry for the long post, but I did search prior to posting. I just don't want to have to get up extra early in the morning to have to deal with this before work. Thanks.

 

[MUSKYMAN]

The block heater is confusing the ECU. When the engine is getting a signal that the engine is warm but its really not it leans out the mixture to the point that the truck will crank and crank untill it finnaly has enough unburnt fuel build up to allow it to fire.

if it just wont start then unplug the thermistor on the top of the manifold, the lack of signal will cause the ECU to go full rich and it should fire right up. Then plug the sensor back in and away you go.

I had the same issue a few years back when we had a week with -30 in northern wisconsin.

 

[Uncletom]

Not sure if the 98 is like my 99 disco1. Had same problem and turned out to be a bad resistor or cold solder joint in my multi function relay box located in right front fender (about 1" X 4" across the top) with 2 multi pin plugs on the bottom. I found if I had the hood open and reached in to turn on the key, you could just tap on this box and the pump would engage instantly. You only have about 10 seconds to do this as the power from switch will turn back off.
I used a small dremal saw and cut around the bottom and lifted off the cover. Inside is the 3 relays and all three have a resister to reduce the current to energize them. The one closest to the bottom switches the full pump power. I used an Ohmeter and found this one to be about 4 time to high as compared to the rest. I soldered in another of approx 75 ohm and now switches on every time.
Something to check. Or replace the unit about $135 from dealer or $100 on line.

 

[Butch]

The block heater is confusing the ECU. When the engine is getting a signal that the engine is warm but its really not it leans out the mixture to the point that the truck will crank and crank untill it finnaly has enough unburnt fuel build up to allow it to fire.

That makes sense, but unfortunately, it happens when the truck is not plugged in as well.

Not sure if the 98 is like my 99 disco1. Had same problem and turned out to be a bad resistor or cold solder joint in my multi function relay box located in right front fender (about 1" X 4" across the top) with 2 multi pin plugs on the bottom. I found if I had the hood open and reached in to turn on the key, you could just tap on this box and the pump would engage instantly. You only have about 10 seconds to do this as the power from switch will turn back off.

I'll have to give this a shot in the morning if it will not crank. The good news is that the check engine light comes when I put the key to pos 2...first time in 3 years.

 

[Butch]

Not sure if the 98 is like my 99 disco1. Had same problem and turned out to be a bad resistor or cold solder joint in my multi function relay box located in right front fender (about 1" X 4" across the top) with 2 multi pin plugs on the bottom. I found if I had the hood open and reached in to turn on the key, you could just tap on this box and the pump would engage instantly. You only have about 10 seconds to do this as the power from switch will turn back off.

You were right on the money. I gave it a few taps this morning and she started right up. How did you test the resistance with the ohm meter? It's been a while since I have done anything with an ohm meter. Thanks.