'98 V70 Starting issues

Klausc · Post by **Klausc** » 28 Mar 2013, 10:40

There are 2 hard lines that come up from the rear of the engine, over the cam. One is the fuel line and is attached to the rail. The other is a vacuum line and is routed to the front of the intake manifold where it is attached with a rubber elbow. This line goes from the intake manifold to the FPR and must NOT contain any gasoline - if it does, the baffle in the FPR is shot.

You are correct, the higher the vacuum the less fuel fuel pressure. So when pressure becomes positive with boost, the FPR raises pressure by about 4psi. If you don't have a fuel pressure guage, use an old pencil type tire pressure gauge and check the pressure at the end of the fuel rail. At idle, it should be around 39psi.

MSLV70 · Post by **MSLV70** » 28 Mar 2013, 11:11

Thanks for the help, Klaus.

The vacuum line from the FPR to the intake manifold seemed dry. The rubber elbow didn't have any clamps, although it appears it did at one time.

I found this thread after I bought the car: https://www.matthewsvolvosite.com/forums ... 8&p=264699

That's the car I bought. He mentions having purchased a new FPR in that thread before he tracked down the problem, so I'm guessing the FPR isn't the problem.

Klausc · Post by **Klausc** » 28 Mar 2013, 12:03

That rubber elbow should have a clamp, when the manifold gets positive pressure from the turbo boost, it could fall off (highly unlikely unless the elbow is old and loose to begin with).

I re-read the start of your post. If the fuel pressure is OK, then it is time to do a compression test. Twice, once on a cold engine and again on a warm engine. If there is a bad injector, it might wash the cylinder walls and remove oil from the rings.
A cold engine will cause the ECU to increase the injector fuel time and give you a richer start and it could be misfiring on a poor cylinder when the engine is slightly warmer.

Have you looked at the throttle body? Has it been cleaned lately?

MSLV70 · Post by **MSLV70** » 02 Apr 2013, 08:44

A quick update... I haven't really had a chance to work on the car, but I did swap in a new fuel filter. No change to the starting issue.

I'll look at some of the other possibilities this weekend.

-Matt

Post by **erikv11** » 02 Apr 2013, 09:10

MSLV70 wrote:... Where should the vacuum line for the FPR go? Mine has a long line run from the FPR that loops from the passenger side (past the coolant tank and ECU), along the front of the car, and then is connected just behind (rear of the car) the airbox. ...

This sounds wrong. The vac line on the FPR should connect to the vacuum tree, on the throttle body, not to the airbox.

MSLV70 · Post by **MSLV70** » 02 Apr 2013, 09:43

Are you sure? I just double-checked and the FPR line definitely runs to a port just to the rear of the filter box and AFM. The vacuum tree located near the throttle body has 5 small ports. 4 are capped and 1 runs to a white/black check valve towards the front of the car.

Post by **erikv11** » 02 Apr 2013, 10:03

I've got three 850s, one of them is a turbo, all three have the FPR at the rail, and the vac line from the FPR runs straight to the tree. The turbo still has the factory hard line with aging rubber elbows, I better fix that once it gets warmer.

On my NA I know the upper port on the airbox runs to the tree, the lower line loops back around to the airbox. Not sure what ports are on the turbo's airbox.

MSLV70 · Post by **MSLV70** » 02 Apr 2013, 10:12

Interesting. The FPR on this car is to the rear of the motor on the passenger side. Near the firewall. The FPR has 2 vacuum lines coming off of it. One runs to the manifold and the other runs just to the rear of the AFM. If I ran the second line to the vacuum tree, it would see boost and vacuum. It currently doesn't see boost.

Anyone else with a V70 AWD want to chime in?

Klausc · Post by **Klausc** » 02 Apr 2013, 10:35

MSLV70 wrote:Interesting. The FPR on this car is to the rear of the motor on the passenger side. Near the firewall. The FPR has 2 vacuum lines coming off of it. One runs to the manifold and the other runs just to the rear of the AFM. If I ran the second line to the vacuum tree, it would see boost and vacuum. It currently doesn't see boost.

Anyone else with a V70 AWD want to chime in?

Your vacuum lines are correct. Because vacuum goes away with boost, the extra line might be to save the FPR from extra pressure. Your car does use only one of the nipples on the vacuum tree, the 850's use one for the turbo gauge in the instrument cluster which was not avail on the S/V70s.

MSLV70 · Post by **MSLV70** » 02 Apr 2013, 10:39

Thanks, Klaus.

'98 V70 Starting issues

Re: '98 V70 Starting issues