High pressure in-tank pump

[JonC]

Hi just wondered if anyone has any advice/opinions on using a high pressure pump in the fuel tank and ditching the under car pump.
I'm considering it as I've had countless pumps die using the stock setup and a walbro 255 or similar is about 1/3 the price of the two stock pumps.
I think the walbro may run maybe 20 psi higher than the stock pump (~100 psi) so I'm wondering if the fuel pressure regulator will handle it ok or if there are other issues I'll run into..

This is for a '91 240 n/a.

[Clifford Pope]

Getting the in-tank assembly out of the tank without damaging the connection pipes, and solving a rubic cube like puzzle to get it back in again, is one of the worst jobs on the car.
Is there really space to get a presumably bigger pump in as well?

What would be the advantage over dispensing with the inaccessible in-tank pump and fitting a slightly more powerful external pump?

[Clan]

If you get a genuine Bosch under car pump they last forever or at least the rest of the cars life if your original has failed .if you are feeding them with properly filtered fuel that is !

What would be the advantage over dispensing with the inaccessible in-tank pump and fitting a slightly more powerful external pump?

well the problems start in the line from tank to pump , the pump will be producing a low pressure in that line which means the fuel will boil at a lower temperature and cause vapour locks on a hot day . thats why volvo fitted the in tank pump to prevent this , another reason is that the big pump under the car is not designed to suck well .In fact if you run out of fuel you may never get fuel pressure again !

Leave it standard volvo knew what they were doing in those days when they had proper engineers !

[JonC]

Originally Posted by Clan

If you get a genuine Bosch under car pump they last forever or at least the rest of the cars life if your original has failed .if you are feeding them with properly filtered fuel that is !

I think the problem is the in-tank pumps failing and starving the main. I got about 30k miles out of the last Bosch and it outlived two in-tank pumps.
The tanks off the car now for sealing and it did have some rust streaks in it so maybe this was the cause.

Anyhoe, I can save $200ish going the single pump route so still tempted..

[Paul240480]

I ran mine for the best part of 3 years with a dead in-tank pump. Main pump 'sang like a gooden' once fuel was round about 1/3rd or so.

I have now replaced the in tank with an OE (see post in articles sec') with the help of cumbrianmale - We were pleasantly surprised with how well it went, certainly not (for me) the worst job.

The main issue is not to snap off one of those metal pipes on top of the sender unit like we did . 'A trip to the scrap yard to scrounge another sender & re-do the whole job later' sorted it.

The original main pump is still there and has so far, refused to die

[JonC]

Well it turned out the roof of the tank was really rusty once I had a good look in there so I'm sure that was the cause of the dead pumps. It's all nicely etched and sealed now so that's good.

Anyhoe I went ahead with the thrifty single pump conversion and here's what I ended up with. It seems to be working just fine but I haven't got around to measuring the fuel pressure yet so I don't know for sure. Its totally silent tho so that's a nice change for me



That's all 1/4" 200psi hose because that was the size of the banjo barb going into the filter. The normal low pressure coming from the tank is 1/2" but very conveniently there was an unused 1/4" tube thru the tank lid thingamajig so I hooked up to that. No adapters or anything and it even went into the tank without much of a fight so quite an easy job in the end.

[crogthomas]

Good job. To give you some confidence that all will be fine, take note that as standard the 940 Turbo models use only one pump, the one in the tank.

[Paul240480]

Hehe, same as an 850 then on which mine died leaving me stranded, lol