As you may, or may not! have heard... when returning from our last 44 trip, in 108* heat, 44's fuel pressure gauge started showing 0 psi, from the aux fuel pump. I switched to the main fuel pump and, with 4 psi, we trucked on.
A while later, the main dropped to 0 psi. I switched to aux, 4 psi, and we trucked on.
After the third or fourth time, I found switching to the other pump didn't help... 0 psi on both pumps... We pulled over, popped the hood and I poured ice on Chester's bed, under his belly, to keep him cool.
I was going to bypass the Pollak, eliminating the electronics and wire directly to the main pump... But, 44's headers run at 450* on a warm day and it was way too hot to work in the engine compartment... So, I figure we'd just limp home.
After about 10 minutes, I started her back up, with 4 psi And we trucked on... Until it next occurred... Sometimes, I could flick the DPDT switch and continue on... Other times, we had to pull over and pop the hood for a few minutes... always refreshing Chester's ice bed.
I think we had to pull over 17 times and cool off... But, truthfully, I tasked Chester with keeping a count and he let me down.
Anyway, we made it home... A long, hot trip... the next day, 44 wouldn't start... 0 psi on both pumps.
Long story, longer... I carry spares for every part in this fuel delivery system and I assumed the heat was messing with one of the electric parts.
I swapped out the Pollak Switching Valve and the main fuel pump started pumping at 4psi... But, the aux pump showed 0 psi. I crawled under and swapped to my spare pump... No change... I put the meter on it and found only 4.5v... Not enough to make the pump... Pump.
I crawled under the oil filter and disconnected the Oil Pressure Safety Switch... Trust me, it's difficult to troubleshoot with the OPSS connected.
I then went to the DPDT switch on the dash and metered the main pump circuit at 10.5v and the aux pump circuit at 4.5v.
This anomaly is very curious... For two years, I have had this fuel system set up, to be powered from the coil+, and never had a problem with it... Now, the same wire feeds to the DPDT... The DPDT switches between main and aux... And, yet, the main always gets the full Monty and the aux only gets about half.
I swapped the DPDT and found the very same result... Not enough umpf to run the aux pump... I reached out to Rudi and he gave me a couple of suggestions... I filed them away, hooked the trailer to the Tundra and we went to Northern New Mexico for about three weeks of delightful cool mountain air and afternoon thunderstorms... We had a great time!!
Returning home, I went over every inch of 44, looking for a short that was energizing the frame or body... Nothing...
I then went over the fuel electronics, yet again and metered the coil, finding that the voltage fluctuated between 10.5v and 4.5v... I don't know whether this is normal or not... But, why would it always be 10.5v for the main pump and 4.5v for the aux pump?!?
At any rate, I decided to change the fuel electronics feed to a different switched source... I found the 'extra' voltage regulator wire (never used) is hot, when the ignition is on, so I wired to that source.
Voila!! Problem solved... Fuel system fixed!!
I rewired the OPSS and all is good in 44's world again... So, I'm hooking the trailer to the Tundra and we're heading out again for a few weeks... I just wanted to be sure Chester and I could get after it, when we return.
Life is great!!
P.S. If anyone feels any of this indicates my coil is failing, please speak up. I carry a spare, but I haven't been able to find any real info on this.