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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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Engine won't rev and huntsViews : 21200 Replies : 509Users Viewing This Thread : |
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Sep 15th, 2019, 08:54 | #61 |
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There seem to be a few different in tank ones so thought if I ordered the wrong one I could send it back, without using it so still in wrapper
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Sep 15th, 2019, 09:34 | #62 | |
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The cap and rotor and new Bosch ones and all the sensors seem to be original Bosch ones too, just don't like the idea of how much they cost!! Is there a way to test the sensor incase the code reader doesn't give anything back? Just so I can be sure!? Thanks for the good information though! |
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Sep 15th, 2019, 09:52 | #63 | |||
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Check the flow on this pressure pump : https://www.rockauto.com/en/moreinfo...1433970&jsn=15 As you'll see, the maximum flow is 40 Gall/hr so the lift pump in the tank needs to flow at least this amount. Therefore 15 gall/hr (aka 75L/hr) is NOT enough. Quote:
Also, even 4.5psi will be enough to make that fuel line hard to squash with finger and thumb. I'm not saying thre isn't a problem with the MAF but if you don't have enough flow from the in-tank pump, it won't rev properly. Have you tried bringing the revs up slowly and gently rather than opening the throttle wide in one go? If you can bring the revs up this way, it suggests the fault is lack of flow/pressure rather than the MAF, especially as the idle went rough when you unplugged the MAF previously.
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Sep 15th, 2019, 10:28 | #64 | |
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My dizzy cap and rotor are shared with 6 cylinder BMWs and no others so are ridiculously expensive, as for the Fuel Pressure Regulator on mine, shared with the 911 and a couple of other now mainly obsolete cars, mostly in the UK i was quoted £3-500 because of that!
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Sep 15th, 2019, 13:10 | #65 |
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Do we know the specs of the original in tank fuel pump? I can't seem to find one online that is definitely original? Surely that way we can look up the flow and pressure and match one?
It definitely says online that the in tank one is low pressure but it would make sense for it to be the same volume output as the high pressure pump to avoid the cavitation, but then again provided the suction is within the fuel tank would it not be able to draw it out of the tank? I might just whip it out l, check for a part number and also check it doesn't work by hooking it up to 12volt. In respect to the revving I have tried opening the throttle both slow and fast, it doesn't seem to make much difference, I can't remember if there's any slight difference but from what I remember there isnt. It's as though as soon as the TPS is signalling open throttle it just goes bad, it tends to hunt the engine though it revs up and down a bit. I can check when I'm at home but I'm working now. Is it possible to upload a video here? When I disconnected the MAF sensor it did make a difference to the idle which leads me to believe it may work but perhaps not properly!? However if this pump is not working it may be best to fix that and then try the MAF sensor? |
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Sep 15th, 2019, 16:06 | #66 | |
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The underbody pump isn't capable of drawing a vacuum to pull the fuel through (hence the need for the in-tank pump) so will not pull extra fuel through a pump that can only supply 1.25L/minute. It might say online it's the in-tank pump (the Valeo one) but don't forget there were also carburettor 740s and (i'm not sure) i think there were a few 940 carbs. Trouble is with sellers, they don't always know (or care about) the correct spec, it took me several days of more or less continual searching to find the original spec. The original Volvo part number is 3507436, if you look through this pdf on Pg20 (by DOcument Viewer Pg number) you will see the part numbers for the "Pre-pump" and cross referencing that to Rock Auto and others comes up with a pump that matches the spec i've already given. http://www.myvolvolibrary.info/Tech_...DataPocket.pdf Bookmark that pdf - you'll need it at some point in the future! As for "just whip it out" - good luck with that! Refer to my pics above, that plstic ring is tight with a capital "F" and needs to go back the same way (i use a piece of wood and a lump hammer to knock the wood, Volvo have a special spanner), once out and the various hoses are disconnected (again, easier said than done!) you pull backwards and slightly upwards on the sender plate. Then you turn it 90 degrees (can't remember if it's left or right and then start pulling the plate towards the back of the car. As the pump and sender start to come out, if you turned the plate 90 degrees to the left when you first turned it, you need to move the plate to the right and draw the pump/sender unit out in a curved motion. Opposite way round if you turned the plate to the right to start after bringing it slightly backwards. THen if you're lucky, you can lift the sender/pump assembly out through the access hole and see the pump. Note how the wires go onto it, 8mm socket if memory serves. Also the strange clip at the bottom that secures the sender to the pump. YOu'll probably find the strainer is collapsed on the bottom or at least blocked. Make sure you don't drop the sealing ring in the tank!!!!! Refitting - you "Haynes it" - refitting is the reverse of removal. I used some silicone grease on the seal and also the plastic lock ring threads to aid refitting and getting it tight. I also found after about two months i needed to check-tighten it with the wood and hammer as it settled and leaked a little. 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!
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Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........ Last edited by Laird Scooby; Sep 15th, 2019 at 17:08. |
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Sep 15th, 2019, 20:42 | #67 |
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Thank you about the info of the ABS / Speedo reading Dave.
New to me. I will store this. The engine won't notice a lift pump not working if the tank is at minimum half full. Lower than this the main pump will produce a vacuum and bubbles are in the fuel. If your car has the same problem with the tank full you save time and money for the lift pump later Good night, Kay |
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Sep 15th, 2019, 21:00 | #68 | ||||
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do you mean because I can run the tank above half way and not pay for the pump haha |
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Sep 15th, 2019, 21:18 | #69 | |
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Not a wise move as it puts undue stress on the main pump. Previous owner of mine did that, i was lucky in that the underbody pump was good enough to keep the thing going when the level dropped but eventually those were the clues that the in-tank pump was FUBAR - it would cut out for no apparent reason, difficult starting, would idle but not rev, not even bringing the revs up slowly/gently. That was why i fitted the NRV as a test, to see if it was dropping pressure back to the tank when it shouldn't. That further exposed the in-tank pump as the culprit.
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Sep 15th, 2019, 22:39 | #70 | |
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I bought the car with the issue so I'm not 100% sure how suddenly it happened, the previous owner didn't use the car in the last 2 years as he lost his leg, he had it serviced for the last year before he passed away and I think it was his gardener that occasionally started the car but I'm not sure at what point the issue arose.
I just saw that the newer pumps are a much higher pressure so thats out the window haha, this is proving to be a bit of a nightmare! I have a friend that works at Volvo so in the slight off chance I asked if he could track anything down. Quote:
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