Author Topic: 1990 tiffin - Is there more than one fuel pump?  (Read 143 times)

Offline Reego

  • *
  • Posts: 6
  • I own: a Motor Home
  • Year: 1990
  • Make: Tiffin
  • Model: Open Road
  • Chassis: Chevy
  • Engine: 454
1990 tiffin - Is there more than one fuel pump?
« on: June 16, 2020, 12:12 PM »
I recently acquired this 1990 tiffin open road built on a 1989 p30 chassis with the 454. The unit sat for a while and I’ve been doing my home work with a lot of help from this site. I used the post that Lefty to prep the engine and got it running with a 5gal gas can. Since it sat i read that i should drop the fuel tank to drain it, clean it and replace the fuel lines and “in tank” pump. While inspecting the fuel tank and fuel lines that run back there i noticed theres a fuel tank drain so i drained it that way and also there’s a carter pump mounted on the frame rail. My question is does is this the only pump (other than the mechanical pump on the block) or does it still have another pump in the tank? I think not and I’ll find out anyway since I’m dropping the tank, just wanna know why the pump is out of the tank, since it looks like the previous owner might of put this one there. 


https://flic.kr/p/2jcuRr6

Online Rickf1985

  • 6 year member
  • *
  • Posts: 5927
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: 1990 tiffin - Is there more than one fuel pump?
« Reply #1 on: June 16, 2020, 03:28 PM »
The in tank pump may have failed or more likely the fuel pump relay failed and they diagnosed it wrong as a bad fuel pump. I will bet that external pump is wired all the way to the front to a switch or other rigged up wiring. I will also bet you are going to find a pump in the tank, and it probably works. While you are playing around with the fuel system there should also be a fuel pressure regulator in the line close to the tank somewhere. Does it still have the engine mounted mechanical pump?

Offline Reego

  • *
  • Posts: 6
  • I own: a Motor Home
  • Year: 1990
  • Make: Tiffin
  • Model: Open Road
  • Chassis: Chevy
  • Engine: 454
Re: 1990 tiffin - Is there more than one fuel pump?
« Reply #2 on: June 16, 2020, 04:17 PM »
Hey rick, yes i ran a hose from the mechanical fuel pump mounted on the block to a gas can in order to get the engine running, i believe the regulator in this model is mounted on the right side frame rail right before the mechanical fuel pump.

Online Rickf1985

  • 6 year member
  • *
  • Posts: 5927
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: 1990 tiffin - Is there more than one fuel pump?
« Reply #3 on: June 16, 2020, 07:44 PM »
That would be the correct place to mount it but I have never seen one of these motor homes have one mounted there. If it is there then you are good to go with that. Should be a Holley regulator. Usually they are mounted in the back in the most impossible to get to spot! And they always fail after 25 years or more so when it comes time to replace the 15.00 part you need to spend hours trying to get to it. So sounds like you are one of the lucky ones.

Offline Reego

  • *
  • Posts: 6
  • I own: a Motor Home
  • Year: 1990
  • Make: Tiffin
  • Model: Open Road
  • Chassis: Chevy
  • Engine: 454
Re: 1990 tiffin - Is there more than one fuel pump?
« Reply #4 on: June 16, 2020, 09:26 PM »
Yes I’ll be replacing it along with all the rubber fuel lines and fuel pumps.

Offline Reego

  • *
  • Posts: 6
  • I own: a Motor Home
  • Year: 1990
  • Make: Tiffin
  • Model: Open Road
  • Chassis: Chevy
  • Engine: 454
Re: 1990 tiffin - Is there more than one fuel pump?
« Reply #5 on: June 29, 2020, 04:13 PM »
Removed the fuel tank to send it out to get cleaned also removed the sending unit to my suspicion it doesn’t have a in tank fuel pump. Does anyone know where i can buy a new one? Or atleast the sensor with the float?