1992 740gl 2.3 Jetronic LH 2.2

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Posts: 1
Joined: Sat Feb 24, 2018 7:56 am
Year and Model: 1992 740gl
Location: johannesburg

1992 740gl 2.3 Jetronic LH 2.2

Post by Benedict83 »

so here is the story, i have recently become the owner of a 740gl , got it for a steal.. basically traded for a laptop. now from when i got it i knew there were some issues to with starting and running. the car did seem to be well looked after and has only 164700km on the clock.. it is in really good nick overall except for the guys prior to me having hacked into the wiring attempting to install aftermarket ECU's and ignition modulaters.. i took all of those things out and started with the basics as follows after seeing it start up on some carb cleaner

1) it had no injector pulse both green with red trace and the gray were live, i then traced fault to the crank angle sensor, replaced it and voila the car idled, albeit a bit low and not smooth.

2) cleaned throttle body and idle control valve

3) found that three wires from dizzy were just hanging loose not attached, fished around and found that brown connects to fuel pump relay on the brown wire there, red i assume a switched live from ignition and black i gather negative.

4) found the intank pump was not working, we cannot get parts locally anymore so i had a look at the pump, cut the top were the edges were rolled over, stripped inards out, and they were very grotty, the positive brush was stuck and not contacting.. got it unjammed, some very light sanding on 800 grit waterpaper keeping everything nice and squared it worked perfectly, reassembled pump bit, got it stuck togethet with stuff we call pratleys steel epoxy here. tested pump in container off a good battery for 30min.. worked lovely.

5) the issue i have is the inline pump by the fuel filter runs non stop, the car will not rev up past 2000rpm unless i get relay to break contact by hand by rocking it back and forth very quickly, parts here as i said are insanely scarce so am having to make do with what i have, i dont think there is anything wrong as such juat that maybe there is something else thats supposed to communicate with ECU to switch relay on and off regarding engine load. i suspect maybe per chance the AMM ( Air Mass Meter) or otherwise known as MAF is faulty but i have no info on testing this or to be 100% certain it is..

if anyone that has knowledge on these cars and these symptoms can help i would greatly appreciate it, just keep in mind i dont have access to the parts in south africa and dont have the funds to just buy up stuff.. i have systematically worked through as much as i can think of.. am i missing a vital element? o btw the fuel pressure on the rail is a consistant 44psi...

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Post by lummert »

Your 740 should have LH2.4

3) If you found a crank sensor then the 3 wires from the distributor are not needed. Distributor used with LH 2.4 has no hall sensor. Apparently someone has installed incorrect distributor.

4) Intank pump is low pressure high volume. Maybe you find something from a GM vehicle with throttle body injection.

5) Main pump should run nonstop when the engine is running. The fuel pump relay is grounded by the LH ECU.

Take time to figure out what you have. LH 2.4 has primitive OBD. Maybe research Volvo On Board Diagnostics.
1988 Volvo 760 Turbo Wagon

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Post by RickHaleParker »

This should be of a help. See attachment.
Volvo 740 1991 Wiring.pdf
(679.58 KiB) Downloaded 68 times
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