changing efi hoses on 78 280z

[no.never]

hey all.

i had a random day off from work yesterday and i decided to fix the fuel leak around the injectors that leaks when the car is cold. i guess when the car heats up the rubber expands and solves the leak. the most consistent leak was at the bottom of my #2 injector, where the metal cup and the green plastic meet. the other two leaks were along the fuel rail. all injectors were clicking.

i was going to town when i got stomped. a couple of the screws on the injectors are either galled or really tight. the bottom ones are really tough to get to and i found a broken retainer, looks like its plastic?. i thought maybe i could just cut the hoses and take the rail out first then the injectors so i can get to the screws but i seem to be missing a manifold bolt because it's not going anywhere. i'll look again. i'm also gonna replace the screws, maybe to hex so it's easier next time. and o rings.

do i need two o-rings in each injector? the FSM only shows one. parts store shows two, top and bottom.

with the new hose can i get rid of the metal cup at the end? i'd feel safer with two clamps instead of one

FSM says to remove the cold start valve along with the rail. do i need to do this or can i just disconnect at the hose?

when installing i'm thinking injectors first then fuel rail on top or maybe all together. other than that the injectors are gonna get tested and cleaned and i'm gonna clean connections around there.

suggestions and tips appreciated

[EuroDat]

Hi no.never. Read this thread http://www.classiczcars.com/forums/thread46931.html It will give you a good run down on how to get them out.

DON'T cut the hoses to the injectors. You can not replace them, they are part of the injector.

The o-ring are not really o-ring, but two square sectioned rings. See my second photo in the thread above. There is a small one at the tip and one under the aluminium bracket where the screw go through. You can replace the screws with bolts. The part numbers are also in the thread above. Just go to your local nisan dealer. I never had any luck with the gaskets at the dealer, but you can get them at Black Dragon, MSA or even ebay.

If the screws wont come loose, try tapping the back of the screwdriver when turning it. The impact often helps release the screws. Then replace them with Hex screw part #01121-02981. You need 12, $.61 each so $7.32. They are stuffed anyway.

You can get to them with a small pair of vice grips, but you need to remove all the fuel piping first. Its hard to get to but its do-able. Be careful not to damage the injectors.

Might be a good time to service the injectors while you got them out. Be carfull when selecting an injector service shop. They are old and dont like the new injector cleaning fluid much. Okinjectors does old injectors. http://hiperformancestore.com/Ljetronic.htm Scroll down to the section where he talks about injectors. Interesting.

Last piece of advice is to download the fuel injection manual from http://www.xenons30.com/reference.html

It has a good dianostic section.

Goodluck Chas

Edited November 8, 2012 by EuroDat
Hex bolt part number

[no.never]

thanks chas! i had read post before i decided to do the job, persuaded me to tackle it. i guess i'm just missing that "invisible force". hopefully the force will be strong with this one. this 280 was supposed to be my daily and so i can learn how efi works. talk about baptism by fire.

[siteunseen]

I was baptized with a fire extinguisher.

[Zed Head]

There is one fuel rail bracket that's bolted to one of the four big intake manifold bolts across the top of the manifold. Looking down from the driver's side (left side) it's underneath the rail so essentially invisible. That's probably the force. Several of us have been stymied by it.

[no.never]

yea after this I'm gonna put an extinguisher inside. Got another day off so ill work on that today. Don't really want to remove the cold start, looks like its never been touched. Maybe to clean it? Does the FSM say what the hose sizes are? I know its 5/16 for the most but I don't remember seeing hose sizes. all the hose info I found was insertion lengths.

[EuroDat]

I used Gates automotive multi fuel 8mm and 13mm clamps http://www.ebay.com/itm/FUEL-INJECTION-HOSE-CLAMPS-5-16-HOSE-SIZE-AUTOMOTIVE-WHOLESALE-PRICING-/380417962705

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. Don't use worn drive clamps with slots in the band for the screw. They tend to cut into the hose. Remember you can't replace the hose section of the injector.

Chas

Edited November 9, 2012 by EuroDat

[Zed Head]

You can replace the hoses on the injectors. It's even described in the FSM as a standard maintenance practice. The injectors have a specific "one-way" barb style that allows the hose to go on and seal but not come back off. The old hoses have to be cut off. I've used the 5/16" Gates hose and it seals fine. You do need a good tight hose clamp on the rail because the new hose is kind of slippery and will tend to loosen up on the rail barbs over many heat cycles. Check the clamps as regular maintenance. The injector barbs don't leak.

[no.never]

Ok thanks. Battling it out with the last screw. I guess I'm removing the cold start or should I cut that section connecting to rail then replace

[no.never]

That last screw was getting the upper hand so I took out the rail and left that one in. The space wasn't much of a difference but at last the battle is won. With two casualties, a coolant hose and a tiny emissions tube?

Looking at my injectors I noticed #5 and #6 looked different shape than the others from the tip, and #6 has either a melted o ring or someone tried to seal a leak.

Also noticed the tips of #1, #2, #4 has a slant at the tip as if something is knicking at it.

Any thoughts?

[EuroDat]

Gratz on getting them out without damaging them.

I would get them serviced by a serious injector service center. They can replace the tips, seals and small inlet filter and then flow trst them.

[Zed Head]

Typical mis-matched injectors on an older Z. If they flow at the same rates the mis-match in pintle caps (the plastic cover on the ends) won't matter. How long has the car sat in the past? It doesn't take long to build up gas tank crud and get a little moisture in the injectors. The set that were on my car when I got it had a mis-match in flow rates of about 15-20%. A few of the cylinders were running pretty lean.

Only the small seal on the end seals to the intake system. The big one is an insulating mounting gasket. The rubber pieces are cheap and available at most auto parts stores.