Fuel Accumulator Life and pressure

[Beachdrifter]

Hi friends,

So I replaced my fuel accumulator about 5 yrs ago. Recently I did a pressure test and noticed that the air intake plate stays hard after shutdown for about 2hrs. And normally restart after 8 hrs the car starter turns about 2 to 3 seconds before car ignites. On cold start up its always instant ignition.

On average how long should a good accumulator hold pressure for ? Ive read any where from 30 mins to 8 hrs. What's average? Is mine less than efficient now?

Thanks for any info.
Randy

[jackb]

From DMC’s Support Page

The most conclusive test of the accumulator is to disconnect the hose from the end of the accumulator that faces the rear of the car. Plug the hose. Connect a second section of 1/4" hose to the nipple on the accumulator and direct it into a suitable container. Start the engine. After an initial spurt of fuel, no fuel should flow from the accumulator. If it does, the internal diaphragm has failed.

See my recent thread on verifying my accumulator was bad, and other items to isolate/troubleshoot.

[Bitsyncmaster]

Mine holds almost three hours. I think my hot start relay may help you but it would still take one second of cranking for it to kick on the CSV.

[Rich]

There are no current problems you mention. You want to see if the fuel system is degrading over time. Or at least the accumulator.

First, it sounds like you know the accumulator isn't the only component that can cause a rapid loss of fuel system rest pressure.

Second, the air metering plate push-test isn't very precise although it's a good fuel pressure troubleshooting technique. There is a real rest pressure test/spec in the DMC manual. If you want to monitor degradation of rest pressure performance over the coming years then you should consider running a version of the factory test on a regular basis.

With a pressure gauge on the primary side of the fuel distributor look for these readings just after engine shutdown and shortly after - factory specs:

Rest Pressure = 3.3 Bar (48psi)
Minimum pressure after 10 min. = 1.7 Bar (25psi)

As to your question maybe somebody on the forum has studied it more deeply and can tell us what "average" is.

Since DMC/Bosch did not specify rest pressure beyond 10 minutes maybe it's not important. Yes, low rest pressure after maybe 15-20 minutes, not only after 10 min., is important but the "10 minute" spec is telling us something either does or does not need attention, that's all. And the techs don't have all day...like we do.

[Beachdrifter]

You guys are awesome, all this is great info and thanks for the threads. Good read for sure. It makes me feel a bit better, looks like things are nominal for the most part. I think the troubles are certain once the pressures fall less than 30 mins.