Engine/Transmission (1998.5 - 2002) Fuel System Relay Failure

[Riflesmith]

I was at full highway speed today when the engine suddenly lost all power. It was still running, but no power and lots of white smoke. Glanced at my fuel pressure gauge--zero psi. Pulled over immediately and truck would idle, but would not take any load. Shut down, turned key to start, no lift pump noise at all. Got into the fuse and relay box under the hood and started swapping relays into the fuel system relay slot. Some would run the lift pumps(I have a pusher pump as well), but not with sufficient voltage to produce much pressure. On the fourth try, I swapped out the relay labeled "security". Got in and the lift pumps sounded normal and produced normal pressure. Drove it home without further incident. I would like to share several observations:



1. A fuel pressure gauge was a very valuable troubleshooting tool.



2. These wonderful "Made in Germany" relays must be junk.



3. Perhaps 24V owners should consider purchasing and adding several relays to their "Roadside emergency kits".



The relays serving various functions have the same numbers on them and seem to be interchangeable. Having several spares would be worth some peace of mind. Personally, I am going to replace all relays of this type on my truck and have some spares as well. Where I live it is easy to find yourself a long way from anywhere.

 

[Gary - K7GLD]

HMMmmm - THAT's certainly interesting - who woulda thought!



Keep us informed as to availability and cost of spare relays... On my truck, the separate relay to run the pusher operates off a spare fuse in the fuse block in the right side of the dash - and SHOULD supply enought fuel to operate the engine even if the main LP fails... I think... It's a plain 'ol Radio Shack plugin relay, easy and inexpensive to replace...



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It's the relay and mount visible upper center of the picture...

 

[Shovelhead]

If all else fails. a jumper wire of sufficent gauge and two crimp on male connectors might get you home if your relay goes Tango Uniform in the middle of BFE.

Just jump the 12V power feed to the load

(just remember to pull your "Cheater Relay" when you get where your going. )

 

[Riflesmith]

Good suggestions. My pusher pump is activated by its own relay as well. However, this relay is activated by 12V being present in the wire to the factory lift pump, therefore it did not run either.



I priced the relays at my local DC dealer, $9. 90 each which they did not have in stock. I'm sure a search of parts houses and electronics dealers will reveal some savings. It shouldn't be too expensive to carry some spares.

 

[Big White Beast]

Good idea......

When I was dinking with my air horns I bought an extra relay because it wouldn't fire the solenoid. (Bad solenoid) Anyway I have spare now. I wasn't able to find one anywhere except the dealer though. It's worth the $10 for piece of mind.



On another thread I talked about firing the pusher relay from the LP wire. It drops voltage at start-up so the VP isn't overpressured. This causes the the pusher relay to toggle. (In cab mounted so I hear it clearly) This I'm sure will take it's toll on that relay also. So I carry a spare for that also.



Just some more to think about.



Garrett