1989 760 turbo - no start - no gas

robin_740 · Post by **robin_740** » 07 Feb 2015, 13:42

greetings all,

picked up this car on Thursday as spares for my 740 wagon as engine looks identical save for turbo; cant seem to find fuel pump, went in under trunk liner - looks like that's just the sender under left side access hole, there is no access on right hand side; is there just one under the car? from my 240 manual I m using (I know!) it says I should have 2, one in tank, one in line under the car; so question is, does 760 have just one pump under the car?

tia (thanks in advance)

Post by **jimmy57** » 07 Feb 2015, 15:49

One is in tank with the level sensor and one is under car.
The fuel pump should run for 1.5 -2.0 seconds every time key is turned to position 2.
This assumes the fuel injection control unit is getting powered up and that the fuel pump relay is functioning and the fuses are OK. The relays are in a center that is on top of trans tunnel facing into passenger side (RH) footwell. The panel that goes under dash on RH side and has a portion that covers the area on top of trans tunnel is removed to see the relays.
Go to volvowiringdiagrams.com and find the one for that car and locate the exact position on relay center where that relay is located and also for the fuel injection diagram.

robin_740 · Post by **robin_740** » 07 Feb 2015, 16:44

thanks Jimmy!

light faded on me tonight, will resume tomm, I have spark, will chk power to fuel inj control unit too; I just need to confirm which pump is not working so I get the correct one and don't source unneeded parts,

many thanks!

lummert · Post by **lummert** » 07 Feb 2015, 20:38

On my 1988 760 Turbo I had an intermittent no start. I eventually traced it to the boost pressure over pressure switch wiring connector having corroded terminals. You will find this switch just in front of the coolant reservoir on the passenger side.

I temporarily fixed my problem by cutting off the harness connector to the switch and connecting the 2 wires together.

robin_740 · Post by **robin_740** » 08 Feb 2015, 15:01

greetings!

Update - so had no power to 87/2 - 30 relay output, traced down blown fuse in driverside door jam dash area and replaced. Tested fuel pump relay, suspected its bad, made fusible link jumper and attempted to crank, still no humm or gas to injector rail. So diagnosis is bad tank fuel pump and relay - on order (ebay cheapest). I noticed the fusible link jumper I made got very hot and blew out 15amp fuse, I replaced with 30amp, but still very hot, ie too hot to touch - is this normal?
Once I get replacement parts I think we should get gas barring no issue with inline pump - thanks to all for input so far - will update you as I progress,

thanks!
rob

lummert · Post by **lummert** » 08 Feb 2015, 15:54

I made a test jumper to jump the fuel pump relay socket. Jump from terminal 30 to 87/1 and 87/2. If the jumper wire gets hot either the pump is shorted out or the wire in the harness is shorted to ground.

robin_740 · Post by **robin_740** » 08 Feb 2015, 20:04

Yes hopefully I do not have any shorts in the wiring and the only short in the system is burned out pump, replace pump and relay and X my fingers! Car should start once it gets fresh gas as we have spark already. Car has been sitting a year, but I am not worried, from research posts, I see someone else got his car going after pump repair and his car was bought after sitting two and half years.
We will play with it again next weekend if parts get here on time.

Post by **jimmy57** » 09 Feb 2015, 07:20

Cars that sit for long periods with the fuels we have had in the US for the last few years can get stuck fuel pumps. Often powering the pump and striking the bottom of fuel tank (left side on this car) for in-tank pump and tapping on the external pump can get them to run again. If you power a stuck pump too long it does fail.

robin_740 · Post by **robin_740** » 08 Mar 2015, 22:33

Update - took the sender out of the tank today, its totally messed up, wires no good, rusted, need new part as installing pump alone will not work.
Located used part on Eb, will fight with it again next weekend,

thanks all for your help so far

following was very helpful

http://www.volvoclub.org.uk/faq/FuelTan ... cement.htm

robin_740 · Post by **robin_740** » 15 Mar 2015, 13:29

ohhhhh boy,

So here is the update - replaced whole sending unit - used got a really good one, bashed n banged n butchered it up to get it in and then its upside down - ugh! Test start, pump does not work now, it tested good connected in trunk before install. I have power all the way up to pump connection so I assume we broken one of the wires going to pump. Why oh why does Swedish chefs make that hole sooooo small? OK, so I m giving up and dropping the tank....a clue here to that all is screwed up is that gas gauge no longer works,,,,,,,boy I have been so tempted to take the sawsal to the trunk of this

thing thing!

regs rob