Need help asap daily car
 

Crap...so I was going to work in the 84 760 D24T hit a massive pothole and the car shutdown. Didn't hear any sounds or anything. Wouldn't start after that, I ended up towing it home. It's pumping gas in to the filter, and turning over and huffing and puffing some smoke but it won't ignite. Very strangely the glowplug light on the dash is not coming on even in the cold...it usually always worked...is it possible I lost a relay?? I know of one large one on the shock tower, same side I fell in the pothole...could it be toast? Could it cause the engine to stall?

Please help soon its my only car and I need to make it to work!!!

Additional details...I hit the bump just before a gear change so the load on the engine was changing...belts seem fine. The vacuum hose which goes from the pump over the head and to the intake manifold.has been disconnected for weeks unintentionally...not sure if that did much.

Thanks!

Hi Rollin. Friend hit an nyc-style deep-@ss pothole then he couldn`t use the car but that was an Automatic with cracked in half mounts at motor & tranny (as often, driver side mount was almost non-existent, metal on metal) Some sensor went crazy and shifter would not move (all new mounts got it fixed) but I`m sure this is not your issue. You can manually trigger the glow plugs if you want to.

Inspect
 

I took a few pict of my glow plug unit, it might help you.
A huge hit on the shock tower can `shake` stuff around.
Some have extra wiring connected straight onto battery terminals so carefully check that too.

As a first step of diagnosis, check wiring, all connectors + there should be a `strip-fuse` underneath there held by two small screws (3rd pict).

Yes you will want to verify GPs are energized during pre-start. Do you have a VOM?

But even if the GP relay or wiring was disturbed, it should have started up immediately, as the engine was then still near operating temp, not requiring GP.

Verify the fuel cutoff solenoid is getting +12VDC when the key is in start and run positions.

Does not make sense to me. Explain?

Did the engine immediately stop on impact or did it continue running for some time? Did it leave an oil puddle? Is the oil pan intact?

More of a pressure hose than vacuum. It transmits turbo-induced pressure from the intake manifold to the top of the IP diaphragm that moves the ramped fuel pin to increase the amount of fuel injected under boost. Disconnected it would reduce performance under boost situations (generally during higher revs, more throttle).

Might have knocked a bit of insulation off the wiring harness.

Update
 

No power to fuel solenoid! None to glow plugs either! No click sound! Looks like the solenoid got stuck, will be investigated, very happy right now. This is saving me a lot of hassle!

Seriously check the engine harness, as stated some the insulation might of fallen off causing a short. I would say that 90% of pre 87? Volvo's on the road have a deteriorating engine harness.

Solved
 

You were right, there was a fault with the wire. I ended up running a new wire to a switch instead because we could not trace the source of the problem but for some odd reason we later discovered that fuse #11 which is overdrive and glow plugs (25A) was blown and we totally forgot to check it before we made our repair...Could #11 have been the issue all along???

:confused::(

Yes, it likely was. The glow plugs are typically on the same supply circuit as the IP solenoids and other engine controls in most of these. Not sure for that particular year but likely to be the case. Probably you could remove that extra wire and change the fuse, and it would work again on its own, for a while... but you'd want to track down whatever harness short caused it to blow in the first place. ;) One common insulation failure point is the 4-wire harness that plugs into the bottom of the GP relay, on the left-hand shock tower, which contains wires that could short that circuit if jostled on a big bump.

Also NB: early 700s are wired differently from later ones, but from 1984.5 onward the wiring for the A/C compressor shares Fuse 13 with the glow plugs and IP solenoid circuits. In diesel 700's the A/C compressor harness can chafe on the low side hose and then lead to a situation where turning on the A/C or defrost intermittently causes fuse 13 to blow and stalls the motor (with no restart). A bit of a dangerous situation in traffic...