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Cold start injector and or pressure valve in FD? Either one could cause leak down.
Cold start is new and the FD is newly rebuilt from Flowtech. Is there a way to test the CSI. Where is the pressure valve on the FD? The allen head screw to adjust the fuel pressure. (I would guess so but...)
If that is correct, maybe dial back the screw until it leakdown doesn't occur? I'm considering clamping one the fuel line at the tank to see if pressure continues to drop...maybe this could rule out or point to the FP check valve??
The allen head screw is your air fuel mixture adjustment, if you have it way rich (clockwise) you may be opening injectors but you should be able to here that. The pressure valve is in back of FD 16mm (I think) nut behind return line fitting, but if it's freshly rebuilt those orings should be fine. You could pull the auxiliary air control line off the cold start valve and look in to see if it is dribbling but if new I doubt it.
Interesting I had my FD and WUR rebuilt and bench tested by Flowtec last month also and my CCP is low unless I apply vacuum which I can't seem to figure out if that is correct. I did have to add 1mm worth of shims to bring my system pressure up to spec, so I'm not a happy camper but that's for another thread. If you clamp off line, right after fuel pump that would tell you if it's the check valve.
Sorry that was long winded.
Ben- We discussed the rapid leakdown issue, either you have a bad fuel accumulator or you have a bad (or missing) check valve at the fuel pump. The only reliable way to check both is to replace each one at a time. Start with the check valve (893 906 093) since it's cheaper.
Ben- We discussed the rapid leakdown issue, either you have a bad fuel accumulator or you have a bad (or missing) check valve at the fuel pump. The only reliable way to check both is to replace each one at a time. Start with the check valve (893 906 093) since it's cheaper.
hi Rob. I know but I just replaced the accumulator and the fuel pump which I replaced last summer supposedly had a check valve on it. Before I tweak the screw, I’ll drop the plate for the pump and check it.
What was the Bosch part number on the pump? The rat's nest of supercessions and consolidation among Bosch's fuel pumps makes it a bit of crapshoot as to whether you get the right pump for the right application. If you buy a 91160810200 for use as pump #1 on a '78 or '79, Bosch says you need an 0 580 464 202. But what's in the box is an 0 580 464 151. And the product sheet in the box says you do not need an external check valve. But that's incorrect. Ask me how I know.
What was the Bosch part number on the pump? The rat's nest of supercessions and consolidation among Bosch's fuel pumps makes it a bit of crapshoot as to whether you get the right pump for the right application. If you buy a 91160810200 for use as pump #1 on a '78 or '79, Bosch says you need an 0 580 464 202. But what's in the box is an 0 580 464 151. And the product sheet in the box says you do not need an external check valve. But that's incorrect. Ask me how I know.
I ordered 91160810200 from Roger but will double check and snap a pic.
What was the Bosch part number on the pump? The rat's nest of supercessions and consolidation among Bosch's fuel pumps makes it a bit of crapshoot as to whether you get the right pump for the right application. If you buy a 91160810200 for use as pump #1 on a '78 or '79, Bosch says you need an 0 580 464 202. But what's in the box is an 0 580 464 151. And the product sheet in the box says you do not need an external check valve. But that's incorrect. Ask me how I know.
Rob, I’m trying to read through your message and you are correct, the supercessions are a bit confusing. So if I have the below, I should be good to go, correct? https://928srus.com/products/911-608...4a2cb7e5&_ss=r
Yes, that pump is correct, it has a check valve sticking out of the outlet.
I’ll double check but I believe that is the pump I installed. Could the check valve have gone bad already? Once I get the gauges hooked back up (have to get my new WUR line plated), I’ll take a video of the fuel pressure when I turn the pump off. It drops close to zero within a minute or so.
Going to reiterate what I said in post #3 take strip off before striking pin. Wish I had listened to my own advice, I hit the pin and shattered the ceramic on the heating element WTF!
03-26-2023, 10:57 AM
