98 volvo c70 fuel pump

Joe_Hun · Post by **Joe_Hun** » 20 Jul 2011, 11:31

last year i change my fuel pump bought it on FCP OEM for $400 install it didnt check the pressure coz I tought it s fine since it ran... now when i check the pressure from the fuel pressure pipe it was giving me 35psi but i know it should be 43psi so i order used fuel pump on erie send me one install it same thing low pressure it was 37-38 psi called them they send me another one now psi went down to 36-37psi call this morning and they said they will send one again... my question is do the pump has the right position when installing the pump coz i did the same exact position when i removed the old one.. am I missing something here.... pls help thanks

Post by **jblackburn** » 20 Jul 2011, 11:57

43 psi before the car is switched on. 37-38 psi is just right at idle.

Post by **Xilikon** » 20 Jul 2011, 12:02

First of all, are there any issues with your engine which lead you to think it's due to fuel pressure ? There are a lot of things which can cause problems, not just the fuel pump.

Joe_Hun · Post by **Joe_Hun** » 20 Jul 2011, 12:34

yes i have 37-38 psi at idle on the fuel pressure pipe before the pump and fuel filter. but when i switch on give me the same exact psi 37-38 psi.. my issue is sometimes when i start the car is it feels it chocked for a sec then start right away and in the morning first start it will start fine but if you drive right away a little bit hesitation and after a few secs it will drive fine for the rest of the day and if you start the car in the morning and let it seat for 30 to 1 min no hesition at all..

Post by **jblackburn** » 20 Jul 2011, 12:50

I'm not entirely sure this is a fuel pressure issue.

Do you see any smoke out the back?

If I let mine sit for a long while (days at a time - that almost never happens), the valve stem seals leak oil down into the cylinders and it's a little hesitant to get all 5 up and running. When that happens, a quick stab of the gas and a small puff of blue smoke, and she's good to go.

Joe_Hun · Post by **Joe_Hun** » 20 Jul 2011, 12:57

actually I dont see any black or white smoke on my tailpipe. it runs perfect except for the morning drive and it shift perfect pick up is good...thats the only problem i have nothing else so i guess i have to live with that lol..

Joe_Hun · Post by **Joe_Hun** » 20 Jul 2011, 12:59

if you check the pressure on the fuel rail i should get 37-38 psi when idling and 43psi if its on the start on only right

Post by **Pauloil** » 20 Jul 2011, 21:00

Joe_Hun wrote:yes i have 37-38 psi at idle on the fuel pressure pipe before the pump and fuel filter. but when i switch on give me the same exact psi 37-38 psi.. my issue is sometimes when i start the car is it feels it chocked for a sec then start right away and in the morning first start it will start fine but if you drive right away a little bit hesitation and after a few secs it will drive fine for the rest of the day and if you start the car in the morning and let it seat for 30 to 1 min no hesition at all..

I think that is called "warm up"

Post by **jblackburn** » 21 Jul 2011, 07:01

Find your fuel pressure regulator near the steering rack behind your passenger side tire, and inspect the vacuum lines to/from it. One of these goes to the front of the intake manifold, and the other goes to the port on the turbo intake tube just after the mass airflow sensor. Find some vacuum line from an auto parts store (its super cheap) and run some messy "trial" lines down there for now. See if that helps you with hesitation or anything - most of your vacuum lines, if they have not been replaced, are probably in very poor shape by now (I think I've replaced just about every single one I can get my hands on on my 1998).