Fuel Pump Relay for 1980 to 199* P30

Bud,

I hit the clicky "Fuel cut-off relay" on your 24AUG post and it took me to a relay on O'Reilly. Then I put my ZIP in and chose a store for "Price and Availability." At that point it said no nearby store had one and price was $120.99. I didn't look at anything earlier for EFI, at least didn't try to.

MEX,

Glad to know the name change from BOSCH to TYCO. I pulled the relay pic up from Amazon, and they also have BOSCH Brand Relays, about $10.

Anything butva geuine TYCO relay is JUNK TRASH GARBAGE LANDFILL. TYCO is the new name for Bosch. Creepy wanna be's almost cost me the toad engine three times. Electric fan relay failure. Tyco costs a dollar or so more but in a bone dry location you won't be opening it up after a year only to find green spongy powder where the coil and contacts were. The TYCO has lasted FIVE TIMES the mileage and calendar time of the pretenders.

J-D:
Not sure what year you are dealing with. The first relay that I posted is the normal fuel pump relay for injected 7.4 engines. The fuel pump relay on second post is not the normal one. Second is for carb engines. Yes, a standard 30 amp relay should perform just as good.

MEX, funny you mention Tioga Pass. We went to Yosemite driving a Subaru Forester. Albeit from the West. We passed an old Lazy Daze on Chevy chassis on the way up. Then pulled over to take a picture and here came the Lazy Daze. Engine actually sounded like it was chugging Little-Engine-That-Could-Style. We found it on the side of the road with the hood open, after stopping at the ranger station. I'm guessing it either starved or vapor locked.
And why I don't recommend the Chevy/350/5.7 in a full Class C. They really struggle on a climb, and this one wasn't pulling a toad or trailer.

Yo! Bud! I was sure glad to be sitting when I clicked on the O'Reilly link and saw $120!!!

Believe I'd be getting a Bosch Relay and Socket



Just have to be a little careful. There seem to be "Bosch" Relays with only 4 contacts, meaning no "back" contact closing an alternative circuit when the relay is NOT energized. OK to use only 4 pins of a 5-pin relay so long as the back contact isn't needed. OP's diagram says it IS needed.

We found where some of the later Workhorse Class A chassis used a "Siemens Relay" that does the same thing but in a different form factor. Carried GM part numbers.

Would still like to know more about the "regulator."

Dozens perhaps hundreds of long motorhomes have made it halfway up Sherwin Grade on US 395 or Tioga Pass CA 120.

OEM mechanical fuel pumps were NEVER designed to pull fuel thirty some odd feet on an uphill angle. They had to have a safety Unattended Key On fuel cutoff and they chose an oil pressure switch.

All it takes is a chassis Service Bulletin to change designs.

OP could have a very early 89 that has a carb and electric fuel pump. They used a fuel cut-off relay like this.
Fuel cut-off relay
I do not have a drawing showing how they are wired in my cheap manual. All the drawings I have show the oil pressure sending unit in the wiring diagram.

I think I've got the gist of this. The 454 has a carburetor fed by an engine-mounted mechanical fuel pump. BUT SOME P-30 models have an in-tank electric pump feeding the mechanical pump. OK so far? The electric pump is powered through a relay. The relay powers the pump IF either, driver is cranking the engine, OR the engine is running, determined by oil pressure.
OP believes the in-tank pump isn't running due to a bad relay or not staying running due to an intermittent relay.
A likely scenario, but... Are all filters new or clean, including the little one in the inlet of the Quadrajet? And, is the mechanical pump good?

Something does not sound right.
In your FPR post you indicate that it is 1989 with a Quadrajet carb, but I find no reference to a fuel pressure regulator being used with a carb.
The fuel pump relay is only shown for throttle body injection and power fed through the oil pressure sending unit. This configuration continued for several years starting in 1988.

enblethen wrote:
The fuel pump relay only pressurizes the fuel system for a few seconds, then shuts off.
The fuel pump run and power is ran through the oil pressure gauge.
What is the problem with the system that you feel it is the relay?
Fuel pump relay

Not quite accurate, read my last post here; FPR Post

j-d, I'll let you know when I return home and go to the storage yard.