I was having problems with our 1998 S70 GLT starting and the Volvo repair shop determined it was the fuel pump. Well the car starts now with the new fuel pump installed but it now takes a few seconds longer of cranking to start the engine. Faulty fuel pump?
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Brian M. - 1998 S70GLT, 1998 S70 GTA

I read somewhere that the cause could either be the fuel pump's check valve sticking or the so-called 'vapor lock' causing it.

Anyway, I was told by the service manager to observe the car over the next few days.
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Brian M. - 1998 S70GLT, 1998 S70 GTA

There is no vapor lock on these engines! If it takes a long time to crank, it is usually the pressure isn't up yet, which could be the pump they put in or a bad pressure regulator.

The pump has a back flow preventer as part of the pump unit. If they screwed that up by not replacing the entire pump unit, just the electric motor, then it will take a good 5-10 seconds of cranking to get fuel to the rail.

Ask the shop what kind of pump they put in.

Klaus
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There is no present time, just the past and future

Thanks for the info, Klaus. They are a Volvo-only repair shop. Part of the description on my invoice reads:
1. 9480152P - Fuel Pump Complete Assy
2. 9434225 - Fuel Pump Relay - red/green skirt 70 all

The service manager said that if it's still a problem after a few days, they would swap the pump out with another one.

Also, I've noticed a faint high-pitch sound coming from the rear of the car while it's idling in our garage (not noticeable outside). This was after they replaced the pump.
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Brian M. - 1998 S70GLT, 1998 S70 GTA

Ask them if you can have the old fuel pump relay, for a backup since that wasn't the problem. I hate it when good parts are replaced for no reason.

The whining sound you hear is the aftermarket fuel pump. I wonder what kind they put in.

Klaus
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There is no present time, just the past and future

Klaus, have you heard of Pierberg? They said that's what fuel pump they put in. They said it's OEM.
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Brian M. - 1998 S70GLT, 1998 S70 GTA

It is like OEM. Close enough. You should only hear the fuel pump when you turn the key to posII before engine start, 1 or 2 seconds to build a little pressure. The engine noise should drown out the pump even at idle.

You might want to check the idle air control motor for noise. It also runs all of the time and if dirty could be noisy and lead to poor air delivery at start up.

Klaus
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There is no present time, just the past and future

Thanks for all your help, Klaus.

One last question: As previously mentioned, I just had the 90k service done last month (new plugs, filters, LOF, etc). Fuel Filter was replaced last week due to non-start. Driving is fine except when starting the car (cranking could take up to 5 seconds) and so service is replacing the Fuel Filter in a couple of days.

Having said all this, I just noticed now that whenever I coast to a stop the RPM would dip to 800 for a moment and then back up to about 850-900. Twice I also felt a faint shudder (like the engine was under load) lasting about a second or so. Is this related to the Fuel Filter?
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Brian M. - 1998 S70GLT, 1998 S70 GTA

Fuel filter is normally good for 100K miles; new Volvos don't even have a fuel filter any more.

In your case, I would suspect the idle control motor is dirty. Or the throttle body needs cleaning?

Klaus
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There is no present time, just the past and future

Sorry, Klaus! I was referring to the Fuel Pump (which was replaced due to non-start), not the fuel filter. My bad. Would the Fuel Pump have anything to do with the RPM drop/shudder?
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Brian M. - 1998 S70GLT, 1998 S70 GTA

It really should not. If fuel is being delivered at a high enough rate to feed the injectors at throttle up, there should be plenty of pressure at idle.

The IAC and throttle control air into the manifold and are the usual suspects when there is a drop in idle at low rpm.

Klaus
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There is no present time, just the past and future

Thanks, Klaus. I will inquire about the fuel pump. Is there an easy way for me to check it myself? I remember I need to remove the trunk carpet or something.

Hmm, with regards to the relay, it could be possible that they accidentally broke the original relay during diagnoses/repair -- but, I don't know.
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Brian M. - 1998 S70GLT, 1998 S70 GTA