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Posted by: cary Jun 25 2017, 10:42 PM

How many folks remove their rain tray in the summer ?

Car didn't want to restart even after sitting 90 minutes at 100 degrees. Did the SOP full throttle crank, but not for 60 seconds like some folks attempt. I was just wondering how much better air flow I would get without the rain tray. After 90 minutes the rubber fuel lines were 150 degrees. The FI rails were still 170. That's bitchn hot after 90 minutes.

Car ran great for the 32 miles to Forest Grove. Got there and checked the dipstick oil temp gauge, 232 degrees. Outside temp 98 degrees. Tinkered with the idle a bit, was running fine. I wish I'd measured the temp on the lines and rails. Shut it down. I went inside to move things around so I could get it out of the hot sun. Came back out about 15 minutes later to drive it in. No Go ...............

Looks like its time to work on my own car. Full tune up and hook up the AFR meter.
I know I'd get scolded by the Cap'n to call it vapor lock. But it doesn't like 90 degrees plus. Temps drop 20 degrees tomorrow so I can't replicate for a while.

Data Points :
2 Port Fuel Pump up Front ......
Changed fuel stations on last fill up..........hmm

Posted by: rhodyguy Jun 26 2017, 06:10 AM

Easier just to source a lid for summer driving and slot the hinge arms for a quick one person change.

Posted by: michael7810 Jun 26 2017, 06:31 AM

I know the perfect place if you want to do some high temp environmental testing. Phx temp drops 2.0 degrees today so it will only be 113F

Posted by: mepstein Jun 26 2017, 07:00 AM

Fill a spray bottle with water. The next time this happens, spray down the fuel pump with the water. It will cool it quickly. If this works, you know you have fuel pump vapor lock.

Posted by: cary Jun 26 2017, 07:33 AM

Gave the one I had to Doug to build a GT lid. I'll come with another one when I repaint my car and build a GT lid for myself.

Posted by: cary Jun 26 2017, 07:51 AM

I was thinking of you yesterday. What is he doing better than I am ?
The poor little car just gets driven. I kind of neglect the adjustment stuff. Oil change no, valve adjustment yes. So it's time.

I'll order Chris's oil pressure relief valve and a plug for my MPS, it's open for adjusting. But for starters I'll pull the air temp sensor and run some bench tests.

I reread some of Capn's writing from way back and he said Porsche never figuring it out. Some ECU's couldn't handle the high heat. Hmm. Bad solder joint on the board?

I talked to Steve Weiner from Rennsport Systems about the oil temps you and I were seeing at WCR. He said no damage has started. You just loose power when the cylinder heads get that hot. That made me feel a little better. I'd never let my car get that hot before.

Posted by: cary Jun 26 2017, 08:00 AM

I'll stop at the $$$ store and add that to my Kit. Hopefully there won't be a next time, but if there is hopefully it will at home. Then I'll go bag up the ice from the ice maker and lay the bag on the pump.


Before I drove out to Forest Grove I pulled 2 of the plugs out of the front panel to get some air circulation around the pump. It was getting pretty hot the day before.
I also removed the spare tire cover and umbrella cover that is carried up there.

I think I'll go ahead and install a fuel pressure gauge on the fuel rail so I can collect more data. Oh yeah, pull the filter for a quick blow test. Just in case it's something simple.

Posted by: michael7810 Jun 26 2017, 09:48 AM

I changed the oil yesterday to Mobil 1 V-Twin 20W-50. I've heard that was good oil for T4 engines and it was on sale so I decided to give it a try. I drove about 40 miles in 100F temps on the highway towards Payson which is uphill and the oil did not exceed 230F. I've driven a lot in the extreme heat and I find to keep the oil temps under 240F it's best to downshift before the heads exceed 375F on hills. If I let the heads get closer to 400F it takes longer at high RPM (4000) to cool them down and high rpm drives oil temps up. Keeps it interesting on long drives

Posted by: mepstein Jun 26 2017, 09:54 AM

If you already have the pump in the front trunk, it's probably not vapor lock. But at least you will know for sure with the spray bottle or ice.

Posted by: cary Jun 26 2017, 06:37 PM

I run V Twin in the 3.2 in my RS replica. I only saw 215 in stop and go traffic on Saturday at 101 degrees.

Posted by: 914_teener Jun 26 2017, 06:49 PM

I thought someone tried this and noted no appreciable cooling.

I take mine out because it makes me feel that it might run cooler.


No science to back it up so it must be true.

Posted by: cary Jun 27 2017, 06:59 PM

Well maybe bad news is good news. I sent the kids and Super In Law to Forest Grove to retrieve the car. No Go. Best they could diagnosis with my over the phone guidance is no power to the fuel pump. Hmmmm.

Beings that I have ZERO 0 confidence in the NEW Uro relays that really doesn't mean too much. I'll let you know what I find.

Posted by: era vulgaris Jun 28 2017, 04:40 PM

In terms of airflow, I did an experiment two summers ago with my old '75 that had a McMark built 2270. I had a 4 channel digital head temp gauge with senders under the spark plugs, monitoring instant head temp changes on all four cylinders in real time.
I spent the entire month of July without the rain tray, and the entire month of August with the rain tray (or maybe it was vice versa, I can't recall offhand). Both months are the humid as hell dog days of summer here in NC. 90-100 degree ambient temps with extremely high humidity.
There was ZERO difference in head temps running with or without the rain tray. Nada.

Unfortunately my oil temp gauge wasn't working at the time, so I can't comment on whether it affected oil temps or not.

I decided I preferred the rain tray because even though I didn't intentionally drive in the rain, it kept all the random leaves, bugs, pine needles, and crap that's flying around out there out of the engine bay. Plus, living in the south there are surprise local t-storms during the summer that can encompass a tiny area while the surrounding skies are blue. It's a good idea to run one, IMO.

Posted by: Elliot Cannon Jun 28 2017, 04:48 PM

Is it possible to run the fuel pump with the engine NOT running? Would that not allow cooler fuel from the tank to circulate to the fuel rails and the hot fuel would return to the tank? I used to have an old Beechcraft Bonanza that was fuel injected and a real beeeotch to get re-started when the engine was hot. Running the fuel pump for 30 to 60 seconds before starting was the procedure. Just a thought for FI engines.

Posted by: bbrock Jun 28 2017, 08:06 PM

There was an ancient tech tip (I think in the old Mid Engine Views mag) where you popped the cap off the fuel relay, drilled a hole in the top just large enough to fit the cap of a ballpoint pin through in such a way that when pushed, it closed the contact on the relay. The idea being that you could manually run the pump with the engine off to purge the lines and cool things down. My first 914 was a '70 that vapor locked constantly. So I tried the mod, and it worked. I'm not saying it was the best way to deal with the problem, but it was an interesting hack that sort of fit the quirky nature of these cars.

Posted by: pete000 Jun 28 2017, 08:28 PM

I don't run the rain tray, but I never drive in the rain either.

I have heard a lot of comments that the rain try does not impede cooling...

Posted by: cary Jun 29 2017, 06:31 AM

I like it .................
Not real difficult with the new Chinese relays, the tops don't stay on. So it would be pretty easy to drill a hole.

Posted by: Mark Henry Jun 29 2017, 06:51 AM

Back in the message board days (maybe very early club days) some engineer 914 owner did temp readings on every lid cooling mod and hack known.
None made any real difference for the better, except a small scoop attached to the sail with a hose running into the right side small engine grill. But the improvement was so slight that he didn't bother keeping it.
IIRC removing the rain tray made it worse, but again only slightly.
He did note the definite difference that the plastic deflectors under the car made to temps.

Totally going from memory, so I could be wrong, but IIRC that was the final verdict.

Posted by: cary Jun 29 2017, 06:54 AM

Well couldn't stand it any longer and ran out to Forest Grove after work at Rothsport.
After testing 12 relays in the fan circuit only 8 fired up. I find that hard to believe. Some were new Porsche in the box. I'll tinker with spreading the pins later.

But still no 12v power to the pump. I get continuity from socket 87 to pin 13 on T14. I get 12v at socket 30 key off. I get 12v at socket 85 key on. But why does 85 it stay on longer than 3 seconds ? Found the answer in Jeff's test procedure. ECU turns off the ground.

I'm beginning to suspect the fuel pump got cooked. Which might have created issues back upstream. I hope not ....................

Starting here after I swap out the pump. I can't let these go until I figure it out .........
http://bowlsby.net/914/Classic/zTN_FI_FPChecklist2.pdf
Cross them off the list one by one ..............

Posted by: cary Jun 29 2017, 11:58 PM

Update :

Fuel pump had failed. Installed spare, swapped around some relays and I'm back in business.

Drove home with a big smile, top off wind in my hair. I left Matt seam sealing his engine compartment.