More help please! Fuel pump question

[Chrisay59]

We have a 1979 240 Excella Motorhome with the original 454 engine. We recently had our inline fuel pump replaced, the one that is bolted to the chassis half way between the fuel tank and the engine. It seems that this electric one is the only one that is working! However since it's been replaced we are experiencing a fault whereby the engine "misfires" under load, by that I mean any sudden acceleration or whilst going up hill. Could it be that the fuel pump that has been replaced isn't giving the correct amount of fuel at the correct pressure? My question therefore is what specification fuel pump do I need? Any help would be greatly appreciated, thanks to all you awesome people in advance.

[bkahler]

I would suggest installing a Carter P4070 electric pump as the pusher pump (or ensure your pump has the same characteristics) and replace the failed mechanical pump with a new one. The Carter fuel pump will ensure a steady supply of fuel to the mechanical pump and the mechanical pump will ensure the carburetor gets enough fuel at the correct pressure.

Brad

[Grosspoluter]

I'm going to assume you meant sudden DEceleration
My personal guess is carburetor problems
Do you know, if you have a mechanical fuel pump bolted to the engine?
My 1984 345 has the same 454 in it
I thought my engine was starving for fuel, when I accelerate it would bog down, under 3/4 acceleration it would work just fine.
I installed electric fuel pump back by the tank when I bought my Motorhome a few years ago
it didn't have electric pump back there
Also I have install a fuel pressure gauge at the carburetor it runs about 4 to 5 PSI on the fuel gauge, The electric pump I installed seems to have helped. But I still have the bog down problem under full acceleration but again I suspect mine is a carburetor problem it just seems like it's running very lean under full acceleration just like fuel starvation
Sorry I couldn't be of more help and I'll be following this post as I'm having almost the same problem

[martin300662]

Originally Posted by bkahler

I would suggest installing a Carter P4070 electric pump as the pusher pump (or ensure your pump has the same characteristics) and replace the failed mechanical pump with a new one. The Carter fuel pump will ensure a steady supply of fuel to the mechanical pump and the mechanical pump will ensure the carburetor gets enough fuel at the correct pressure.

Brad

I have the Carter P4070, and had the mechanical pump removed. The electric pump really helps as, if you turn on the ignition and wait for 3-5secs, it primes the carburetor and so starting is much easier (especially when it is hot and fuel lines vapor lock). But you really need a low pressure, 4-8psi pump (different from an EFI pump), if not you will recirculating large amounts of fuel around the bypass/return line.

The only downside I have found to using the Carter was when the battery went flat; I felt the engine ran uneven until the battery was back up to charge so seriously considering adding a Carter mechanical pump back in series.

I do have a spare Carter P4070, that I carry in case of failure, that I would happily loan you if you want to give it a try?

[Boom Sounds]

My coach also bogged down on occasion. It's a different set up, with the TBI, but I had the throttle body rebuilt and replaced pretty much everything hanging off the engine/iac valve, pcv valve, tps, injectors, sensors, coil, distributor,leads etc etc. Never had a problem since.


Sent from my iPhone using Airstream Forums

[WayneG]

I went through numerous fuel supply problems when I went from a carb to TBI http://theouterlimits.ws/projects/ai...ressureProblem
Some of them that may be part of a carb only problem are as follows:
1) Check your real tank fuel level, one of my problems way a fuel guage that read 1/2 tank when empty. Every time I accelerated or hit a corner, the fuel pump would suck air and I would start stalling.
2) Check for water in the fuel, check the pickup screen for being clogged and check the fuel filters for clogs. When I pulled my tank there was 2 hand fulls of loose rust particles in the tank.
3) Make sure your electric pump can pull air as well as fuel, since the tank pickup tube is higher than the pump, it needs to be able to suck the gas up 2 feet before it gets into the pump. When some electric pumps run dry, they wont work. Also be sure there are no leaks between the tank & pump which will pull air faster than fuel.
4) Check your carb float. I had a brass one in my old Argosy, it got pin holes in it and it sunk, flooding the engine, (with similar effects of lack of fuel)

[davejay]

Hey,
Before you go buying stuff, and taking things apart, you may have a slug of bad fuel. Water in the fuel will give you that problem. Throw about 6 bottles of heat in the tank. Run some octane boast too. Is your electric pump working. I have this 325 with 5K miles on it . The rear electric pump was frozen up. Put a new Holley electric one on, fired the unit up, still nothing. Taped the new fuel pump with a wrench, boom, it stats up. Go figure. You ll hear it running kind of a buzzing noise.
You could also have carbon deposits on the valves. That will act like a burnt valve and cough sometimes. Spark plug wires will do that too. It s always missing, but under a load it becomes real pronounced. DJ

[Chrisay59]

What a relief, bought a Carter P4070 Fuel Pump and fitted it today, replaced a garage fitted pump (i discovered that it was a Headi 1216 12v, totally wrong pump, only delivering 60ltr per hour! And it was poorly fitted, inlet pipe was being crushed by tie wraps). Drove my Silver Machine up the hill out of the city, and she was cruising at 60mph with lots more in the tank, no loss of acceleration...what a relief, I now have my baby back! Thanks guys for all the advice and help!

[martin300662]

Great news Chris, just in time for another festival this weekend?

[Chrisay59]

Originally Posted by martin300662

Great news Chris, just in time for another festival this weekend?

Lol the fuel pump issue didn't stop us from attending our music festivals, went to one in Trowbridge last weekend, off to Upton on Severn Blues Festival this weekend, it just mad me nervous going up ANY incline!

[Isuzusweet]

Gosh, reading all these threads on fuel pumps, carburetors, spark plug wires, coils and such makes me work up a real appetite. How do you guys have time to camp?

Cheers
Tony

[Chrisay59]

Originally Posted by Isuzusweet

Gosh, reading all these threads on fuel pumps, carburetors, spark plug wires, coils and such makes me work up a real appetite. How do you guys have time to camp?



Cheers

Tony

Lol like I said, it's a labour of love!

[bkahler]

Originally Posted by Isuzusweet

Gosh, reading all these threads on fuel pumps, carburetors, spark plug wires, coils and such makes me work up a real appetite. How do you guys have time to camp?

Cheers
Tony

Ahh....the diesel troll strikes again....

[kidjedi]

Getting ready to move my new-to-me 1976 24' Argosy from the neighbor's yard to my driveway (a couple of blocks). The only information I have on why it has been sitting for five years is that when my neighbor's buddy was trying to get it running, he bought an electric fuel pump that wasn't big enough. Seems like a weird reason to give up (a $30 part?), but that's all I know. The new (shiny!) pump he installed is there, mounted on the tank with an inline fuel filter before it. The pump does look a little anemic, so maybe the story is true.

In researching replacing the mechanical pump on the 454 big block with an electric one, quite a few people have mentioned the Holly Red, but at $130 I'm not sure it's worth the "Holly" premium. The Carter P4070 mentioned in this thread is priced at around $60, which is nearly double the price of the other pumps (with numerous good ratings) I've been looking at online, but I like that the Carter is rated to 72GPH in free flow (more than double a lot of the other pumps I was looking at).

In other threads I have seen that it's good to remove the old mechanical pump and place a plate over the old mounting port. I am hoping to find a good thread or blog post that details this process, but hoping I'm alright leaving it as is just to get the rig home. It would seem that a lot of people just leave the mechanical pump attached after installing the electric one, but I have seen reports of issues when leaving a non-working mechanical pump installed.

We made sure the brakes were working last weekend (added about four tablespoons of Dot 3 to the reservoir and just pumped the pedal!), and I pulled the starting and house batteries out to replace them. I had it hooked up to my Jeep with jumper cables, and all the house lights, etc. seemed to be working great, but obviously I wasn't getting enough current to the starter to make anything happen (the starter was clicking though!).

Hopefully the new battery and fuel pump will get this thing to fire up next Sunday. After five years of sitting, I am anticipating having to drain and replace the fuel, but maybe I'll get lucky. I'm pretty excited to get her back to my place to start the rest of the restoration (which will be minimal on the interior... I can't believe how good this thing looks)!

As always, thanks to everyone who takes the time to post and converse. It makes all this fun possible!

[bkahler]

Originally Posted by kidjedi

Getting ready to move my new-to-me 1976 24' Argosy from the neighbor's yard to my driveway (a couple of blocks). The only information I have on why it has been sitting for five years is that when my neighbor's buddy was trying to get it running, he bought an electric fuel pump that wasn't big enough. Seems like a weird reason to give up (a $30 part?), but that's all I know. The new (shiny!) pump he installed is there, mounted on the tank with an inline fuel filter before it. The pump does look a little anemic, so maybe the story is true.

In researching replacing the mechanical pump on the 454 big block with an electric one, quite a few people have mentioned the Holly Red, but at $130 I'm not sure it's worth the "Holly" premium. The Carter P4070 mentioned in this thread is priced at around $60, which is nearly double the price of the other pumps (with numerous good ratings) I've been looking at online, but I like that the Carter is rated to 72GPH in free flow (more than double a lot of the other pumps I was looking at).

In other threads I have seen that it's good to remove the old mechanical pump and place a plate over the old mounting port. I am hoping to find a good thread or blog post that details this process, but hoping I'm alright leaving it as is just to get the rig home. It would seem that a lot of people just leave the mechanical pump attached after installing the electric one, but I have seen reports of issues when leaving a non-working mechanical pump installed.

We made sure the brakes were working last weekend (added about four tablespoons of Dot 3 to the reservoir and just pumped the pedal!), and I pulled the starting and house batteries out to replace them. I had it hooked up to my Jeep with jumper cables, and all the house lights, etc. seemed to be working great, but obviously I wasn't getting enough current to the starter to make anything happen (the starter was clicking though!).

Hopefully the new battery and fuel pump will get this thing to fire up next Sunday. After five years of sitting, I am anticipating having to drain and replace the fuel, but maybe I'll get lucky. I'm pretty excited to get her back to my place to start the rest of the restoration (which will be minimal on the interior... I can't believe how good this thing looks)!

As always, thanks to everyone who takes the time to post and converse. It makes all this fun possible!

Bite the bullet and buy the P4070. As Martin mentioned you can use it with or without the mechanical pump. If possible locate it close to the tank. Electric pumps work best when they are close to and as low as possible in relation to the tank.

Back when Airstream was building the Classic motorhomes the P4070 pumps were installed at the factory. What I don't know is if these were installed by GM or Airstream. Either way they are a good pump and you won't regret installing one.

Good luck!

Brad

[kidjedi]

Originally Posted by bkahler

Bite the bullet and buy the P4070. As Martin mentioned you can use it with or without the mechanical pump. If possible locate it close to the tank. Electric pumps work best when they are close to and as low as possible in relation to the tank.

Yeah. That's what I'm thinking. I've got it in the Amazon cart. Was just finishing up some reading before clicking "buy." And yeah, I plan on mounting it where the previous guy had placed the "too small" pump, right on the side of the tank. Although, looking at the size of the Carter, it may be too large to fit there.

Originally Posted by bkahler

Back when Airstream was building the Classic motorhomes the P4070 pumps were installed at the factory. What I don't know is if these were installed by GM or Airstream. Either way they are a good pump and you won't regret installing one.

Thanks, Brad. I've been going through all your posts, and I really appreciate the time you've put into making advice and information available to those who go after. You rock.

EDIT: Aaaaaand of course all the suppliers (including Amazon) are experiencing supply delays on the Carter pump, so I don't think I'll be able to get one before next week.

[ROBERT CROSS]

Originally Posted by Chrisay59

We have a 1979 240 Excella Motorhome with the original 454 engine. We recently had our inline fuel pump replaced, the one that is bolted to the chassis half way between the fuel tank and the engine. It seems that this electric one is the only one that is working! However since it's been replaced we are experiencing a fault whereby the engine "misfires" under load, by that I mean any sudden acceleration or whilst going up hill. Could it be that the fuel pump that has been replaced isn't giving the correct amount of fuel at the correct pressure? My question therefore is what specification fuel pump do I need? Any help would be greatly appreciated, thanks to all you awesome people in advance.

Does this retired GM Knuckle Buster, Grease Monkey, Mechanic, Auto Technician, Computer Assisted Parts Changer to an Associate with dirty hands and a desk remember a pick-up sock filter that gets sucked closed on the pick-up in the tank? Kinda.🤔

Bob
🇺🇸

[bkahler]

Originally Posted by ROBERT CROSS

Does this retired GM Knuckle Buster, Grease Monkey, Mechanic, Auto Technician, Computer Assisted Parts Changer to an Associate with dirty hands and a desk remember a pick-up sock filter that gets sucked closed on the pick-up in the tank? Kinda.🤔

Bob
🇺🇸

Bob, Chrisay59's post was made back in 2017.....

Hopefully he's resolved the problem by now

[bkahler]

Originally Posted by kidjedi

EDIT: Aaaaaand of course all the suppliers (including Amazon) are experiencing supply delays on the Carter pump, so I don't think I'll be able to get one before next week.

You're not the only one suffering ordering issues. I've had a bunch of orders canceled over the last couple of months

Believe it or not the U.S. stockpile of the correct Olympic rivets has just about dried up.......

[kidjedi]

Originally Posted by bkahler

You're not the only one suffering ordering issues. I've had a bunch of orders canceled over the last couple of months

Believe it or not the U.S. stockpile of the correct Olympic rivets has just about dried up.......

I saw that you were lamenting that in another thread. Aerowood was running into the same issue trying to find rivets all the way back in April when there were still possibilities of some of us getting together in Denver to learn his riveting magic... but that of course went out the window with the bathwater.