1998 S90 Cold Start problem

purplebeauty · Post by **purplebeauty** » 30 Sep 2018, 21:52

New owner of a 1998 S90 with only 91K miles. Car is in great condition, previous owner did a lot of maintenance and drove it mostly long distances.

I want to make sure I get my terminology right but I think what's happening is a cold start problem. When the car sits overnight or longer without being driven, the first time I try to start it, it never fully starts. I believe the language is "it never turns over." I turn the ignition all the way, it sort of begins to start and then dies. But pretty reliably, the second time it does start up. And then after that first drive, it has no problem starting up the rest of the day. Then the process starts over again the next day.

I see the FAQ https://www.swedishautoparts.com/S90/FA ... d_to_Start on this but I sadly am so new to DIY repair that I don't know where to start in diagnosing (and then fixing) this problem.

Any ideas on what this likely is and what the steps would be to diagnose?

Post by **RickHaleParker** » 01 Oct 2018, 06:10

Try turning the key on until the dash lights up and wait 15 seconds before you crank it over. Report back how it behaves.

purplebeauty · Post by **purplebeauty** » 01 Oct 2018, 23:12

Following your directions, it started up like normal! What do you think this means?

Post by **RickHaleParker** » 02 Oct 2018, 11:23

It means your fuel rail pressure is bleeding off overnight.

Here is what is going on, the fuel rail pressure bleeds off overnight, when you you go to start it in the morning, it is fuel starved. Waiting 15 seconds gives the fuel pump time to get the fuel rail pressure back up.

Causes could be a number of things, leaking injector(s), leaking check valve ... ect. Before you start throwing time and money at it. Use your eyes and nose to search for leaking fuel. Add some Sea Foam to a full tank of gas, see if cleaning up the fuel system will clear up the problem.

purplebeauty · Post by **purplebeauty** » 02 Oct 2018, 18:25

RickHaleParker wrote: ↑02 Oct 2018, 11:23 Add some Sea Foam to a full tank of gas, see if cleaning up the fuel system will clear up the problem.

Thanks for this. To be clear, you just fill up a full tank of gas and then add in the Sea Foam afterwards in the fuel tank? Just want to make sure I have that right.

93Regina · Post by **93Regina** » 02 Oct 2018, 21:16

purplebeauty wrote: ↑02 Oct 2018, 18:25To be clear,

Not quite, two steps are required:

1. Techron® Complete Fuel System Cleaner - "I always treat my cars to this in the fuel tank every oil change! Doing it for years and I've never had a fuel injector problem in any of my vehicles for the past 30 years. My Mercedes mechanic told me about it.

2. Fill up with Top Tier Gasoline always...no excuses

Footnote - Study Shows Top Tier Gasoline Worth the Extra Price

AAA analysis reveals that gas with detergent additives can keep an engine running smoothly

Post by **RickHaleParker** » 03 Oct 2018, 03:58

If you fill the tank with gas first, where you going to find the space for the Sea Foam? ........
Put the Sea Foam in first, that way your have the space for the Sea Foam and the two will mix as the tank fills.

purplebeauty · Post by **purplebeauty** » 03 Oct 2018, 11:42

93Regina wrote: ↑02 Oct 2018, 21:16
purplebeauty wrote: ↑02 Oct 2018, 18:25To be clear,
Not quite, two steps are required:

1. Techron® Complete Fuel System Cleaner - "I always treat my cars to this in the fuel tank every oil change! Doing it for years and I've never had a fuel injector problem in any of my vehicles for the past 30 years. My Mercedes mechanic told me about it.

2. Fill up with Top Tier Gasoline always...no excuses

Footnote - Study Shows Top Tier Gasoline Worth the Extra Price

AAA analysis reveals that gas with detergent additives can keep an engine running smoothly

Good info to have. Thanks for this!

lummert · Post by **lummert** » 03 Oct 2018, 16:55

No problems with my 1988 760 Turbo wagon as long as I only run top tier gasoline.

93Regina · Post by **93Regina** » 04 Oct 2018, 12:25

lummert wrote: ↑03 Oct 2018, 16:55I only run top tier gasoline.

Many years ago, I had a 1981 VW Rabbit Pickup with Bosch CIS fuel injection, which constally flows fuel thru injectors. Before government mandated a basic detergent package in all gasoline fuels, if I filled up with cheap gas, within short period of time, those injectors would not be delivering full volume. So, I had to use Techron, and then fillup at an Amoco station which had a good detergent additive, but a much higher price

Bosch's LHs or even Regina's EFIs are similar to Bosch's CIS, except there is fuel injection timing. So, with this setup, a larger diameter injector orifice is used than CIS's smaller diameter. If you look at GM's two injector TBI for a V8, used in a "carburetor" setup, their injector orifices are much larger, due to lower "rail" pressure, and due to more cylinders to feed. Generally, the smaller the orifice, the quicker it can get restricted.

Even in a water district's piping, as more volume passes thru a pipe (injector), there is generally, a decreased chance of plugging up.

But, with Bosch LH or Regina injectors, using Top Tier is prudent, along with using Techron once a year., or so