New to the V10.. Low fuel pressure

[Jrork]

HI everyone. We recently purchased a 2001 motorhome that's based on the F53 with a V10. I noticed that it seems to be hard to start and while it has a strong cranking action, it takes a bit to get it to fire.

I checked the fuel pressure and sure enough, with no fuel pressure showing it takes quite a bit of cranking before it even shows 10 lbs. A bit more and it gets to 20 lbs and starts. It stumbles for a second and then smooths out as the pressure gets up to a high of 28 lbs. Rev the motor a bit and it drops to about 24 lbs.

I swapped out the fuel filter and there was no change.

I disconnected the fuel pressure regulator and instead of the pressure climbing much, it only raised about 1 lbs.

I'm thinking I've narrowed it down to the fuel pump but wanted to double check first. Any thoughts or suggestions?

Thanks everyone.......John

[2bzy2c]

Thank you for reporting back the solution. We will all learn from it.

[cj7365]

Jrork wrote:
Here's the last update. Once we removed the pump we found the rubber hose from the actual pump to the sending unit housing was in horrible shape and was deteriorating. The bottom of the tank had all sorts of pieces of rubber from it and what was left of the generator pick up too. It too was falling about in my hand. Swapped out the pump and shazaam, it fired right off and holds pressure versus how it use to be where the pressure would bleed off almost instantly after you turned the key off. Thanks again everyone

Did you end of just replacing the pump or the whole fuel pump assembly, what part did you use?? where did you get it?

[tderonne]

Fuel line used inside a gas tank needs to be SAE 30R10 rated. It's expensive and tough to find. Regular high pressure hose will deteriorate.

Gates submersible fuel line

[Jrork]

Here's the last update. Once we removed the pump we found the rubber hose from the actual pump to the sending unit housing was in horrible shape and was deteriorating. The bottom of the tank had all sorts of pieces of rubber from it and what was left of the generator pick up too. It too was falling about in my hand. Swapped out the pump and shazaam, it fired right off and holds pressure versus how it use to be where the pressure would bleed off almost instantly after you turned the key off. Thanks again everyone

[tropical36]

Wes Tausend wrote:
...

Another vote for seriously considering using the old sender/mount hanger assembly and just replacing the pump cartridge. Although most net searches will return a variety of brands of pump, I believe most OEM get their pumps from a root manufacturing source called Walbro (a USA pump manufacturer) and put their own sticker brand on it.

All the pump has to do is pump enough to support the HP range. Your V-10 has around 300HP and it takes a certain amount of gas to achieve that over a 4 cylinder for instance. That 300 HP puts you in the range of a common 255LPH (255 liters per hour) pump which will support up to 500HP. The excess fuel is returned via the regulator and return line, or the pump voltage is adjusted/pulsed to furnish what is needed, very little at idle, a moderate amount at mid-throttle for instances. Modern F.I. may seem complicated but it is far from rocket science and all world vehicles now use essentially the same tech for port injection (such as the V-10).

Such pump cartridges may sell direct for little over $100 and, being an OEM supplier, Walbro has always been top quality in the past.

As an example, here is a Walbro 2003 F550 V-10 pump for $108. All 2 valve V-10's are similar HP and the small-truck-only 3-valve HP are just a bit above at around 360 HP, both V-10's same size pump catagory however.

You will probably find that your Motorcraft cartridge will fit by itself if you cannibalize the new one and want to blow the big bucks on it. Otherwise you should be able to find Walbro pumps here: walbrofuelpumps.com. $99.99 with free shipping.

Good luck.

P.S.
I forgot to mention that some gas tanks when left parked for a long time (without adequate fuel submersion) tend to rust the fuel level sender which is usually part of the hanger assembly. In that case your fuel guage may be inaccurate and you will benefit from finding a new hanger, or at least proper parts to replace the fuel level indicator part.

Wes
...

Good post and interesting that you mentioned Walbro, which was the brand I used on my Miata replacement.

[rwynkoop]

You should take a fuel pressure reading with the return line clamped shut with a vise grip. This will tell if the pump is bad.

Could it be you fuel system check valve(in the pump) is bad, letting fuel drain back, and that is why you have the long crank times.

You said specs were 30 - 45 right?

Also, never replace a electric fuel pump without first checking voltage drop with a digital multimeter.

To do a voltage drop check:

- Jumper the fuel pump on at the relay.
- Take a long jumper wire lead and hook it to battery POS.
- Hook you meter neg to the long jumper lead.
- Hook you meter pos to the feed(pos) terminal at or near the pump.
- Your volt reading on the meter should be .05 or less.
- A higher read means the wire to the pump is bad.

You can do the same procedure for the fuel pump ground.

You can find this explained here:
Schrodingers Box - Youtube auto repair help
and here
ScannerDanner - YouTube Auto Repair

Never use a test light on a computer driver circuit.(You can fry it. Use a DVM only. This is computer driven.)

What that said, I think you do have a bad fuel pump. It should hold fuel pressure when off.

I did find this:
Article for Ford Chassis hard start diagnosing.

[liborko]

I recently replaced my fuel pump/sending unit assembly on 2002 F53 with V10 engine. The Motorcraft #F7UZ-9H307-DC (PFS-66). To my best knowledge this pump is made by Delphi and a replacement pump only is available for around $80.

[Wes_Tausend]

...

Another vote for seriously considering using the old sender/mount hanger assembly and just replacing the pump cartridge. Although most net searches will return a variety of brands of pump, I believe most OEM get their pumps from a root manufacturing source called Walbro (a USA pump manufacturer) and put their own sticker brand on it.

All the pump has to do is pump enough to support the HP range. Your V-10 has around 300HP and it takes a certain amount of gas to achieve that over a 4 cylinder for instance. That 300 HP puts you in the range of a common 255LPH (255 liters per hour) pump which will support up to 500HP. The excess fuel is returned via the regulator and return line, or the pump voltage is adjusted/pulsed to furnish what is needed, very little at idle, a moderate amount at mid-throttle for instances. Modern F.I. may seem complicated but it is far from rocket science and all world vehicles now use essentially the same tech for port injection (such as the V-10).

Such pump cartridges may sell direct for little over $100 and, being an OEM supplier, Walbro has always been top quality in the past.

As an example, here is a Walbro 2003 F550 V-10 pump for $108. All 2 valve V-10's are similar HP and the small-truck-only 3-valve HP are just a bit above at around 360 HP, both V-10's same size pump catagory however.

You will probably find that your Motorcraft cartridge will fit by itself if you cannibalize the new one and want to blow the big bucks on it. Otherwise you should be able to find Walbro pumps here: walbrofuelpumps.com. $99.99 with free shipping.

Good luck.

P.S.
I forgot to mention that some gas tanks when left parked for a long time (without adequate fuel submersion) tend to rust the fuel level sender which is usually part of the hanger assembly. In that case your fuel guage may be inaccurate and you will benefit from finding a new hanger, or at least proper parts to replace the fuel level indicator part.

Wes
...

[tropical36]

Jrork wrote:

tropical36 wrote:

You might be better off with getting an OEM replacement and hopefully you can return the one you have now. Try Amazon first, then maybe Mills supply, along with many others for a discount over your local Dealer.

Thats where my frustration is from. This IS a factory Ford Motorcraft complete pump assembly in the factory box and it won't work. Cost $600 over the others that were 1/2 the price but I figured it was worth the added expense. How much you wanna bet the aftermarket one would have been just fine and I'd be done.... 😞

OK, my bad and I keep forgetting that we're talking Ford here and Motorcraft is a product of Ford.
So, does the old unit have any kind of part number on it?
Here's another idea, without actually seeing the thing and I once changed the fuel pump in a Mazda, but not the whole assembly. Just the pump itself (aftermarket in this case) and I think the way to go, as long as the pickup tubes....etc...are in good condition. Also, as food for thought, while you're inspection things, I found that the real problem was that the electrical connector inside the tank for the unit was burned pretty bad and being that it was only available with the whole unit, I made up my own connector and one that wouldn't ever fail. Had the car for years after, my cousin owned it for awhile and it was still going good, when he sold it.

[Jrork]

tropical36 wrote:

You might be better off with getting an OEM replacement and hopefully you can return the one you have now. Try Amazon first, then maybe Mills supply, along with many others for a discount over your local Dealer.

Thats where my frustration is from. This IS a factory Ford Motorcraft complete pump assembly in the factory box and it won't work. Cost $600 over the others that were 1/2 the price but I figured it was worth the added expense. How much you wanna bet the aftermarket one would have been just fine and I'd be done.... 😞

[tropical36]

Jrork wrote:
ARGH!!!! Yep, After taking measurements we opened up up the floor and sure enough, there's a nice big hole there with the fuel pump setting right there.

The bad thing is the million dollar motorcraft fuel pump I got from Rock Auto is the wrong one!!!! This chassis has 3 nipples. Probably one for the fuel to the motor, one for the fuel to the generator and then one for the return. The the motorcraft pump I have here in the box only has one nipple......

You might be better off with getting an OEM replacement and hopefully you can return the one you have now. Try Amazon first, then maybe Mills supply, along with many others for a discount over your local Dealer.

[Jrork]

ARGH!!!! Yep, After taking measurements we opened up up the floor and sure enough, there's a nice big hole there with the fuel pump setting right there.

The bad thing is the million dollar motorcraft fuel pump I got from Rock Auto is the wrong one!!!! This chassis has 3 nipples. Probably one for the fuel to the motor, one for the fuel to the generator and then one for the return. The the motorcraft pump I have here in the box only has one nipple......

[tropical36]

Jrork wrote:

tropical36 wrote:


Take another look at where your holding tanks are located, as what you're saying, doesn't sound right. Obviously the black tank end is going to be directly under the toilet and the grey tank probably alongside it from either port or starboard. When replacing such, both usually have to come out just one side, so double work if your problem is with the inside tank. Not always I guess, but this I've seen.

Tropical36 for the win! I started looking closer at the bolts that hold the tank on and there was no way that we could get any tools to them and the7 built the basement compartments tight to the bolts. Only way to access them would be to cut a hole in the walls of the compartments. Given that, it made me look closer at what Tropical suggested. Aerbus had some nice covered panels in the compartment that houses the waterheater and while they were a pain to remove (just lots of screws), it provided a view between the floor of the motorhome and the "plate" that is above the chassis frame. There appears to be about 12" of space. While it's still too cramped to crawl in there and do anything, what we did find was that there appears to be a hole already cut in the plate and covered up with some insulated material. I'm betting that it is already located over the top of the sending unit. All we have to do is lift up the water tank (under the bed) and either cut a hole or possibly, there's already a hole there since Aerbus has provided a access hole on the plate. Stay tuned and wish us luck!

Good that you're getting there and an hour of extra thought and looking, can sometimes save 6 in the long run.
I keep wondering if there'a already an access plate under our fresh water tank, which is located under the bed, also. Most likely not, as one person did decide to go for it in a coach like ours and ended up having to cut his own, but anything is better, than dropping the tank.

[Jrork]

tropical36 wrote:


Take another look at where your holding tanks are located, as what you're saying, doesn't sound right. Obviously the black tank end is going to be directly under the toilet and the grey tank probably alongside it from either port or starboard. When replacing such, both usually have to come out just one side, so double work if your problem is with the inside tank. Not always I guess, but this I've seen.

Tropical36 for the win! I started looking closer at the bolts that hold the tank on and there was no way that we could get any tools to them and the7 built the basement compartments tight to the bolts. Only way to access them would be to cut a hole in the walls of the compartments. Given that, it made me look closer at what Tropical suggested. Aerbus had some nice covered panels in the compartment that houses the waterheater and while they were a pain to remove (just lots of screws), it provided a view between the floor of the motorhome and the "plate" that is above the chassis frame. There appears to be about 12" of space. While it's still too cramped to crawl in there and do anything, what we did find was that there appears to be a hole already cut in the plate and covered up with some insulated material. I'm betting that it is already located over the top of the sending unit. All we have to do is lift up the water tank (under the bed) and either cut a hole or possibly, there's already a hole there since Aerbus has provided a access hole on the plate. Stay tuned and wish us luck!