Engine won't rev and hunts

[Laird Scooby]

Originally Posted by ANDTWENTY

DONE! It's on its way and should be here for Thursday!

Just need to track down the tank seal now...
would the old one be any good do you think?

Try this part number for the seal, fairly sure it's correct and the one i used when i phoned my local Volvo main stealer to order it :

https://www.volvopartswebstore.com/p...0/1367623.html


Part Number: 1367623


Don't order that from the USA, ring a Volvo parts dept, quote the number and get them to check it's the right one for your car - it should be as yours is 1990 so won't have the later, larger tank. I believe though the later ones used the same seal, including the V90 so should be right.

You might get away with reusing the seal once but the chances are it will be deformed and not seal correctly. The MoT tester doesn't like it when petrol drips on his head!

Also once you've done the job of pulling the sender/pump unit out, you'll realise why i say renew the seal when you do it! It's worth the £11 for a new one so you don't have to do the job again in a few months!

[ANDTWENTY]

Originally Posted by Laird Scooby

Try this part number for the seal, fairly sure it's correct and the one i used when i phoned my local Volvo main stealer to order it :

https://www.volvopartswebstore.com/p...0/1367623.html


Part Number: 1367623


Don't order that from the USA, ring a Volvo parts dept, quote the number and get them to check it's the right one for your car - it should be as yours is 1990 so won't have the later, larger tank. I believe though the later ones used the same seal, including the V90 so should be right.

You might get away with reusing the seal once but the chances are it will be deformed and not seal correctly. The MoT tester doesn't like it when petrol drips on his head!

Also once you've done the job of pulling the sender/pump unit out, you'll realise why i say renew the seal when you do it! It's worth the £11 for a new one so you don't have to do the job again in a few months!

Thanks for that, just gave Volvo a call and its on its way for Thursday too, £10.60 or something he said! he used my reg and got the same part number as you so thats good!

[Laird Scooby]

I thought it was still a current part and the price hasn't altered much either!

[Dopski]

Originally Posted by Laird Scooby

Going totally off-topic, just for Kay, how to convert a speedo that expects pulses from a diff with a 96 tooth reluctor ring (1988 models with ABS) to read correctly on a 48 tooth diff :


Before ^^^^^


After ^^^^^

A bit brutal but SMD has never been my thing, even 30 years ago and time and other things mean my paws are no longer steady enough so i had to blob the solder on instead. It's linking pins 9, 10 and 11 on that chip, 10 is N/C so doesn't matter but pin 9 is the Q3 output from a binary ripple counter chip and pin 11 is Q2 output, in other words, Q3 = divide by 8 and Q2 = divide by 4 (2 to the power of 3 and 2 respectively) so the same technique could be used to fit a 48 tooth axle to an originally 12 tooth axled car in theory.
Just the ABS ECU to convert now! That's still expecting 96 pulses per turn as well!

Sorry for going off-topic but i remember Kay said in one of my threads about not being able to do it, just wanted to show it is possible!

*** EDIT *** Nearly forgot, you can upload a video to YouTube then copy the "Share" link from there into you post as a link.

If you want to upload photos, use a photo hosting site such as postimages.org and select the "Hotlink for forums" by clicking the blue button at the end of the link then paste that where you want the photo to appear in your post.
Other photo hosting sites are available, i use postimages as it's free and easy to use - it has to be as software is not my strong point!

Sorry for going more offtopic. But im very interested in the 48 to 12 divider. Where is this element located and wich pins do i need to connect for that specific application? ( i want to use an G80 axle on my 740).

[Laird Scooby]

Originally Posted by Dopski

Sorry for going more offtopic. But im very interested in the 48 to 12 divider. Where is this element located and wich pins do i need to connect for that specific application? ( i want to use an G80 axle on my 740).

What year is your 740? Also how many teeth on the G80 diff?

[Dopski]

Car: 86 non abs 740, probably 12 Dif: not sure but probably 48.
Otherwise i will cut teeth of the ring gear.

[Laird Scooby]

Originally Posted by Dopski

Car: 86 non abs 740, probably 12 Dif: not sure but probably 48.
Otherwise i will cut teeth of the ring gear.

Almost certainly a 12-tooth ring on the diff at the moment, if you can find out for sure on the new one whether it's 48 or 96 that would help.

If you cut the ring gear/crown wheel, you're likey to cause more problems than enough. The teeth (for actually moving the car) are likely to be case hardened so cutting the crown wheel will weaken it, this could cause it to shatter in service - also put it out of balance which wouldn't do your bearings any favours! Also the sensor is nowhere near the actual crownwheel.

As far as i know, the converter was only fitted to early 7xx cars with ABS and is clipped to the ABS ECU bracket. As far as i'm aware, the 96 tooth diff was only fitted to 1988 Model Year so later cars with ABS are likely to have a 48 tooth and the right ABS/Speedo converter but the 940 it seems had a speedo set up to read the 48 tooth sensor directly.

All of this is guesswork on my part except what i've found through research because Volvo changed so many things for no apparent reason.

[Dopski]

Ok just opened the new 940 axle.
Its an 48 teeth one. The teeth are on a tone ring wich does not have a significant weight i guess. Easy to cut with a dremel or even with a sirious wire cutter.

Read some experiences with this mod on a 240. Some needed to space out the sensor a little more out.

Probably the best way to go for me.

[Laird Scooby]

Originally Posted by Dopski

Ok just opened the new 940 axle.
Its an 48 teeth one. The teeth are on a tone ring wich does not have a significant weight i guess. Easy to cut with a dremel or even with a sirious wire cutter.

Read some experiences with this mod on a 240. Some needed to space out the sensor a little more out.

Probably the best way to go for me.

Depends what sort of tone ring it is. If it's like the 96 tooth ring on my old axle then you won't be able to do that.



If it's like that and you cut teeth out, the ring will fall off because it's a thin sheet of metal and a shaped, intereference fit, similar to some ABS reluctor rings on some cars.

There are some other rings that are thicker plate with holes punched out to create the "teeth" in between the holes. If it's that sort, cut 3 out, skip 1, cut the next 3 and so on to keep it balanced mechanically and electrically. If the ABS ECU sees several pulses and a big gap it will trigger a fault, likewise it will make the speedo jumpy.
I know you don't have ABS but i added that to explain what the electronic side will "see".

Good luck with it anyway!

[ANDTWENTY]

So, the fuel pump arrived, I picked up the seal from Volvo and after about an hour it's all back together. I turned the key with a grin on my face but that soon left when I put my foot on the accelerator and found myself swiftly back at square 1 😭

Also, I tested the old pump on the battery and it works, there is still not really pressure in that line but I am getting 12 volts or battery voltage so pretty confident that it's not the pump. Perhaps it's the other fuel pump? Theres enough pressure for idle supplied by the tank pump but not for revving?

Just checked for fault codes and all I get is no signal from idle air control valve, cleared it started the engine and it came back again, could this be the cause? Did the sensor check function and the rpm, throttle sensor etc where fine, not sure how it checks the MAF sensor, will look that one up again.