1998 Volvo v70 xc - awd fuel pump issue?

[lookforjoe]

Useful resource! Gave me the impetus to cut the floor rather than drop the tank.

OEM style connectors for the fuel lines are available - they are 5/16 quick connect. In my case, I'm installing a DW300 high output pump - requires an extension to the inlet to locate in the stock sender base.





wiring is reversed, so new connector has to be splice & soldered in place



sender ready for reinstall. Since this pump has no side pickup for the fuel that is fed back in the crossover pipe, I cut an opening in the casing to allow the return fuel to drain into the tank



SUR&R quick connect fittings



Thanks to all the others who helped with pics!

[jimmy57]

I'd like to see how this works out. After I spent more money than the new lowered price of the complete pump and sender assembly, I still had fuel starvation with less than 1/4 tank and incomplete pumping of the left bladder of tank.
I did not cut floorboard nor remove suspension. The RH trailing arm removed, the VC extension housing bolt removed, and the over the axle exhaust pipe removed (TX car, this was accomplished with WD-40 and some faint hammer tapping) allowed me to drop rh side of tank enough to get to pump easily. I might also I add I did this repeatedly.
I gave in and purchased the new pump unit complete and it was perfect until I sold the car.

[lookforjoe]

Yes, that method I an aware of - the local Volvo techs do it that way. Since I'm also upgrading all my fuel lines to 10mm, adding an external high volume pump, and a new Adjustable FPR ( I already have one that fits in the stock pod location), I decided greater access is desirable.

General overview:


Tank pump/ filter revision (left drawing)


Using 99-00 filter bracket



My original pump hasn't failed (160k) it just cannot provide the fuel volume for my 4bar 725cc (precision 6262bb turbo @ 18psi) setup. Data logs show fuel pressure drop ( and AFR leaning out) over extended WOT pulls in 3rd & 4th (M66 AWD conversion);

[jimmy57]

You have done a lot of research and I have no doubt you'll sort it out. With your goals you may have to come up with alternate solution for the right tank pick up and running low on fuel may have to be avoided at all costs. I'm not impressed that the right side ejector pump setup to feed the pump enclosure will be adequate to not starve the high flow system with a high consumption engine at the other end.

[lookforjoe]

Indeed. That right side feeder is a concern. I'll see how it plays out. I'm counting on the higher volume return helping in terms of fuel transfer from the left saddle. I can always add a low pressure, high volume in tank pump on that side to push fuel over to the right saddle.

I'm stuck around 425WHP until I get the fuel mods done. I'm sure with all this, I will have enough overhead for at least 500 WHP, If I chose to raise the boost into the mid twenties (the 6262bb is barely at a brisk stroll at the current 17-18psi). I have to also switch over to VEMS standalone for better performance management. All in the works. Anyways, this has little to do with the thread topic.

[reggie1364]

Thanks to all on this forum, the information is great. Here is my problem. About four weeks ago I came out from work and my '98 V70 XC would not start. It would turn over, but did appear to be getting fuel. The tow truck driver confirmed spark and towed it. The mechanic there said it was the fuel pump, said it would be about a 10-11 hour job and $1500. He was able to get it started by banging on the gas tank near the fuel pump. I drove it for about a week, when the same thing happened, and I was able to start with the soft hammer to the gas tank. About three or four days later it stalled while driving home, about 100 yard from a service place. The battery had also been drained while trying to start this time. Their master mechanic confirmed the bad battery and the fuel pump, and quoted about $1800 to fix the fuel pump, with the pump itself around $600. Since I had already been on this site, I mentioned the process of cutting a hole and replacing the pump, but they wouldn't attempt that fix. I talked to one other mechanic that wouldn't go cutting either. So I used the write up by Brian and this forum to order the part from rmeuropean.com (less than $200!) and got the car home to do this repair myself. I used a Rodman nibbler to make the hole, which went fairly smooth for first time using that tool. The disconnects from the old pump did come off with the fork tool, but took some time. The problem I had, which I didn't realize until after I had the car home, was the nearly full fuel tank. Tried siphoning, but that didn't work. Saw on some site that someone said the pan that the fuel pump resides allows for fuel pump removal without losing gasoline. I was a little skeptical, and had something to catch the gas in case. Once I removed the old pump, the gas was coming out. Was able to get new pump in fairly quick, but still a mess and odor problems. I continued with the fix, splicing the new pump to the old wiring harness. Needless to say, and why I'm posting, is that the car still won't start. Turns over, but won't start. Since the hole is still open, I would say that the pump is not getting power or otherwise not working properly, as I can't hear anything from the pump.

My next plan of attack is to:

1) Check fuel rail
2) Check fuel pump relay
3) recheck all of my splices
4) replace fuel filter

Does anyone have any other suggestions?

Thanks!

[precopster]

A definitive fuel power test is of course power at the fuel pump, however this is difficult to measure and could be dangerous. A better approach is to buy piercing test leads for a voltmeter which are sharp enough to touch the copper cable just prior to the fuel pump yet leave no damage on the surface of the cable sheathing.

Also by jumping positions 15 & 87 on the fuel pump relay, this should provide constant power to the pump.
Of course you can hear the fuel pump each time the ignition is cycled to PosII. Also the shraeder valve at the end of the fuel rail will squirt fuel when pressed if the fuel pump is creating pressure.

What I fear in this case is the vibration that the hammer blows were causing were simply resonating through to the fuel relay and reclosing the solder joints on the relay board which are usually the full extent of the relay problem.

[reggie1364]

I've replaced the pump, but the system still doesn't work. Today I've checked the fuel at the fuel rail (schrader valve), and there was nothing. With key in pos II, I checked the voltage at the fuel pump fuse, and it was 12.2V, when I removed the main relay this dropped to 0.15V. I then removed the fuel pump relay and put a fused jumper wire - still didn't start - so the relay is OK. Since I now have the access hole to the fuel pump, I rechecked the splices (2 White, 1 Red, and 1 Black) that I made installing the pump. One of the whites was loose. I respliced and still no starting or pump operation when in pos II. Since I may have crossed up the whites on installing the new pump, I redid those connections - still no starting the car or seemingly pump working. This is where it gets interesting. With ignition in pos II, I checked the Voltage between the red and black wires on the pump side of the splice (butt connector), and got nothing. Same thing on the other side. However, when measuring from red to one of the whites, I measured 8V, between whites I also got 8V. Between black and one white I also got 8V. I'm lost. What should I do next?

[Ozark Lee]

The white wires are for the fuel level sensor, measurements between those and the red or the black wires don't mean anything. What you are looking for is battery voltage between the red and the black wires.

The "polarity" on the white wires doesn't matter, the sensor is purely resistive. You can also check for voltage between the red wire and the chassis. If you get a good reading there then you have a bad ground connection and you could just make a new ground.

The next place to check is at the connector below the access hatch behind the right rear seat, below the cargo compartment carpet.

...Lee

[reggie1364]

Lee, thanks. Was looking at the old fuel pump just before reading your post. Good to know about the white wires.

When the key is turned to pos II, I get nothing (voltage wise) with the red wire - for both pos II or cranking the engine. So, I moved to the access hatch behind the rear passenger seat underneath the cargo carpet. When I measured the voltage at that connector upon the key going to pos II, it jumped up to 4 V, then down almost immediately. When cranked, it went up, but not all the way to 4.

When I get another chance, I'm going to jump the fuel pump relay again, and measure the voltage in the back.

Thanks for all of your input, it has all been very helpful.