Modern injectors, new fuel rail - no heat soak problem

[Zed Head]

The time from shutoff to restart really needs to be noted. 5-10 minutes: generally OK, 30 minutes on: generally OK, 10 - 30 minutes: most likely time to have restart issues. Congrats on getting the car running well.

I did have ~3 seconds of what felt like the old problem today after a long drive, in hot weather (high 80's), with about a 20 minute stop before restarting. It cleared up right away, but gives the impression that the problem can still be induced, but the threshold is much higher, which should make the problem time window much narrower.

On the heat pipe principle: I wonder if someone could build a "worm" (saw the word on a moonshiner shows on the Discovery channel) or distillation coil between the rail and the FPR or the inlet to remove heat. Just seems like a lot of heat to remove through six small injector bodies.

Here are few links about heat pipes. I learned the technology from Kona Corp. before they got bought. The second link has a good picture. In our case, no wicking, just gravity.

http://www.synventive.com/aboutus/default.aspx?id=44342

Endless-sphere.com ? View topic - Definitive Tests on the Heating and Cooling of Hub Motors

I might start an aluminum fuel rail survey over on Hybridz.org to see if there's a trend. pallnet has sold a few barbed rails so they are out there.

[siteunseen]

There's 2 with aluminium rails in that thread I linked, Willoughby Z and 280~Master. They live down here where it gets pretty hot so they might be able to share their experiences on the hot restarting problem.

[Zed Head]

Thanks, I sent them both a message, we'll see if they get back. I also posted over on Hybridz to pallnet to see if a person could buy his barbed rail, with the potential for modifying to o-rings later. But, apparently, his o-ring rails have the holes offset so it wouldn't be a straight hole-enlarging operation. Mine are centered with no issues, so it should be doable for anyone building their own rail though.

I bought the rossmachineracing scratch and dent rail off eBay. Same as shown in your thread, just saved a few dollars. It only had a few extrusion swirlys as defects, otherwise it was in great shape. He sells the good stuff there also.

I'm filling up the forum, break time.....

Raw Dash 6 Fuel Rail Sold by The Foot Scratch and Dent | eBay

Raw Dash 6 Fuel Rail Extrusion Sold by The Foot RMR 019 | eBay

[ZCurves]

So was the fuel rail already drilled for barbs? Or did you have to drill & barb for correct placement on the Z? Pics are good, please post some... As I read about deleting the original Fuel Rail and all of the other related crap...it really has me thinking about going clean on the intake manny.

[Zed Head]

The material comes from rossmachine drilled lengthwise but otherwise there are no other holes. Here's a member who just received a pre-made rail, Post #138.

http://www.classiczcars.com/forums/open-s30-z-discussions/50066-280z-full-restore-5-months-hopefully-2.html#post455933

If you're not handy with tools, like drills and taps, and don't want to run around looking for fittings, the pre-made rails aren't really a big premium over replacing stock parts, or trying to make your own, once you add up the drill bit and taps and fittings and rail.

Edited May 6, 2014 by Zed Head

[Zed Head]

I realized over the last few days that the person suggesting the heat pipe theory, FastWoman, has her fuel rail wrapped with insulation, and little sign of the heat soak problem. But she does have FJ3 injectors. One more reason to wonder. It's hard to get a grasp on a single solution for the problem.

Still haven't heard from the two other guys with barbed aluminum rails. Probably out enjoying the spring weather.

Edited May 6, 2014 by Zed Head

[FastWoman]

Zed, to be more accurate, I have a split rubber hose over my rail, wrapped with silicone rubber tape. The intent was certainly to insulate, but I don't know how effective the rubber really is. It's entirely possible that if I remove it, my hot restart will go away (and my intake manifold will take a small aesthetic setback).

[ZCurves]

The material comes from rossmachine drilled lengthwise but otherwise there are no other holes. Here's a member who just received a pre-made rail, Post #138.

http://www.classiczcars.com/forums/open-s30-z-discussions/50066-280z-full-restore-5-months-hopefully-2.html#post455933

If you're not handy with tools, like drills and taps, and don't want to run around looking for fittings, the pre-made rails aren't really a big premium over replacing stock parts, or trying to make your own, once you add up the drill bit and taps and fittings and rail.

Thanks for the tip. I am all good on tools/skill for this one... I see my next project!

[Willoughby Z]

...still have the measurements if anybody wants them, thanks again Willoughby. http://www.classiczcars.com/forums/fuel-injection-s30/43897-make-fuel-rail.html, #21.

Anytime! My head swims a bit when the engineering chat gets deep but I can measure with the best of 'em!

[Willoughby Z]

I realized over the last few days that the person suggesting the heat pipe theory, FastWoman, has her fuel rail wrapped with insulation, and little sign of the heat soak problem. But she does have FJ3 injectors. One more reason to wonder. It's hard to get a grasp on a single solution for the problem.

Still haven't heard from the two other guys with barbed aluminum rails. Probably out enjoying the spring weather.

Only on Saturdays and Sundays, sailing the Great Chesapeake Bay! Lately, I've been working the NY/NJ area, so I've been absent from the forum. Thanks to Zed's inquiry, here I am.

The car has always had the hot start problem and still does. It also leaks down after a couple of hours. I added a Parker Fittings check valve between the inlet to the rail and the the stock fuel filter, in case the check valve at the pump was ineffective, replaced the FPR, replaced the injectors and cold start valve. In spite of the leak down in pressure, the car always starts with a blip of the key, other than the conditions being textbook for a hot start stumbling, throat clearing few moments.

Stock 77 config, with the exception of an aluminum straight flow fuel rail. It's not a Pallnet, mine is round, with barbed fittings, one to the cold start valve.There is a Summit FP gauge threaded into the side. No brackets. I replaced the injectors a year ago (?), purchased from MSA. I believe them to be Bosch- according to the part # on the box but others have said that MSA doesn't do Bosch. Whatever. I'll double-check when I'm home again. The injector mounting blocks are plastic (MSA), they were metal. I trimmed the FI hose on the top of the injectors, down to about an inch, inch and a half, otherwise the gauge on the rail was to close to the underside of the hood.

Let's see, what else? 93 octane. Tail pipe shows slightly rich, plug read says otherwise, nice mocha toasty color. 28 mpg last weekend on a cruise up RT 17, Norfolk to Fredericksburg, return trip via I-95., 17 deg BTDC. I do need a valve adjustment. Temp gauge runs a little under midway.

I haven't added much, just some some stat data.

Cheers to Zed for the efforts.

Kris

P.S. Here's what I do to to fund WILBY's care-taking...

[Zed Head]

Thanks for the addition. The pressure leak-down could be a factor. Is your FPR lower than the rail or higher? Siteunseen's look higher in his pictures, which would just blow vapor past the FPR, leaving liquid behind. If the FPR is low, then the liquid gets pushed out, leaving the rail dry. Just working on the heat pipe/heat pump/"cooling coil" theory.

The other difference might be the injectors. I did a little internet work and find that the four hole injectors that I have are called "multi-hole" type and the stock and the Bosch are "pintle". The Standard FJ series appear to be their own design, a variation on the Bosch design, according to their web site. Maybe the internals of the injector are a factor. Posted a couple of links below. The SDS description does not match the Bosch diagram for the multi-hole. Not positive what's inside my 280 150 901 injectors.

I removed my cooling fan completely the other day. No more reaching under the dash to turn the timer on. My obsession with heat soak is diminishing...

Nice metal work. I assume the new rail is of similar shine and detail.

Tech Page

Injector Spray Styles - Tech Corner

Standard - Fuel Injectors

Edited May 9, 2014 by Zed Head

[Zed Head]

We just finished a mini-heatwave here, broke some records, temps in the 90's and high 80's, and I've been driving all over the place, parking, shopping, doing stuff, and no sign of heat soak. Still unclear if it's the injector change (Bosch 280 150 901 or Standard FJ707T), the aluminum straight-shot rail, or a combination of both, but there is hope.

Just a follow-up as summer arrives, for those heat-soak sufferers.