Community Forums

fishingjohn · 04-07-2012, 02:24 AM

I have a 1994 national dolphin with a ford 460cto camp ground ran great. We stayed 4 days when we were ready to leave it would not crank. It would turn over but not crank. Did my on checking would crank on starting fluid but go dead. So I checked the wire to fuel pump no juice. I do not have owners manuel so had no way to check relays. I ran a jumper wire to fuel pum cranked and run fine all the way home. Does anyone no where I can start to check why no power to fuel pump. I thought at first there was something that was holding it out as a saftey like a jackdown or something. This is are first motorhome so we are new to this. Just bought it 2 weeks ago. Previous and only owner 80 years old and had a stroke so no help.i. took it on trip 300 miles

Richard S. · 04-07-2012, 06:44 AM

I will attach a link below for the Ford manual, it only goes back to 1996.

You have a fuel pump shut off switch down on the inside of the firewall by your left foot also a fuel pump relay check fuse box. Both would be a good place to start. link below

http://www.motorcraftservice.com/vdi...d=&kevin=rules

subford · 04-07-2012, 07:29 AM

Well it makes a big difference if it is a 1993 F53 or a 1994 F53. One uses fuses and relays in a box and the other uses fuse links and separately mounted relays.
I will guess that it is a 1993 F53 because you said it is a 1994 National Dolphin 32D F53 Chassis.
You can find the year by checking the 10th digit of the VIN.
R=1994, P=1993, N=1992.
You may even have a 1992.

Let me know the year of the F53 by posting in this thread and I will try to help you more.

But check the inertia fuel shut off switch as Richard S posted above. Image of the inertia fuel shut off switch is at the end of the white arrow in the photo below. Just push down on the button on top. It was tripped it will click.

By the way cranking or turning over means the turning of the engine by the starter motor or commencer (the original name for the starting motor).
It will start or starting means it will commence running on fuel either by the injectors or by starting fluid sprayed into the air induction system.

If you do not use the right terms it makes it hard for someone to help you as it throws off their thinking as they read your post.

/

Richard S. · 04-07-2012, 10:25 AM

subford,
Thanks for jumping in, your knowledge is must helpfull.

fishingjohn · 04-07-2012, 03:41 PM

Thanks for the help guys. The 10th digit is R so its a 1994. And to clear it will crank and run with a jumper wire to fuel pump. I checked the switch by the left foot it was not tripped.

subford · 04-07-2012, 04:24 PM

OK, 1994.
Start by checking the fuse "R" in the fuse/relay box in front of the radiator.

If the fuse is good then check the fuel pump relay. It should click as soon as you turn on the key and then drop out one second later. If it does not do this swap the fuel pump relay with the horn relay. See if the horn works, if it does the relay is more than likely a good one.

If the fuel pump relay does not click when the key is turn on and the relay is good then ground pin #6 of the self-test plug and turn on the key. The fuel pumps should run all the time the key is on.

If the fuel pumps will run and the relay will click with pin #6 grounded and not with pin #6 not grounded then the PCM Computer is more than likely bad.

Note that is fuse link "F" and not fuse "F" below. Fuse link "F" is connected to the starter relay or POS (+) side of the chassis battery. There is no connection between the yellow wire from fuse link "F" and the red wire in the diagram below.

/

fishingjohn · 04-07-2012, 05:36 PM

It was the relay thanks so much. You saved me time and money.

Wanabee FTer · 04-07-2012, 05:42 PM

Great thread and great info to remember!

nightriderrv · 05-26-2012, 08:37 PM

I got a MH that is doing the same thing as was described my relay is new it will pull in for the 1 sec key on and it will click when I ground pin 6 but I'm not getting power out, remove the relay put the jumper in and it will run till the tank goes dry, fuse R is good, thing is during the key on no power is coming through. Where to check next???

subford · 05-27-2012, 08:49 AM

If you are putting the jumper in the fuel pump relay socket and jumping the two pins in the socket and the pump runs. Then the pumps do not run with pin 6 grounded and the key on with the relay clicking closed then you either have a bad relay, wrong relay or a bad relay socket.
There is nothing else there that would be bad.

nightriderrv · 05-27-2012, 01:59 PM

I'm thinking socket too because the old relay is doing the same thing, I get no 12v going through when 1 sec prime power when key is turned on, I can hear the relay cycle in and out after 1 sec so that tells me that part is working. when I ground out pin 6 I can here relay cycle in and out also but no 12v, some where in the mix I'm loosing the 12v power, when I do the key and the pin6 test I have no 12v at the inertia which is the last point from there it goes to the pump...unless it's the yellow wire in the back of the fuse block slipped out or I can be pushing the connector out of the back of the block. From what I see the relays are doing what there supposed to do just losing the 12v to make the fuel pump run

subford · 05-27-2012, 02:56 PM

Maybe this will help, it is the wiring diagram of the 1994 F53 Fuse Relay Box showing the Fuel pump wiring in blue and the power relay wiring in red:

/

nightriderrv · 05-27-2012, 08:45 PM

This is good I should beable to trace back to the loss of 12v from all the other checks I've done it's all working but the loss of the 12v to run the pump motor is the main issue thanks I'll be getting to it on tuesday thanks again!!! I'll let you what I find

nightriderrv · 05-31-2012, 08:41 PM

Well got it running no jumper needed after reviewing the correct diagram I found that someone who was there before me messed with the fuses there were a few that were in the wrong location after seeing the correct diagram moved everything to where it needed to be it started with the key as it was designed to