fuel injector

I'm planning on replacing one fuel injector in my 89 because it seem to "leak" fuel - by this i mean i can smell it, the injector looks to be damp, and there's a fine mist coming from around the bottom of the injector where it goes down into the engine when it's running. It started leaking a little at the end of last winter and now that it's getting cold here again it's leaking again. The o-rings were changed last year by a complete idiot who didn't set the rail on good and one or two injectors had their o-rings coming out from where they mount to the fuel rail.

so my real question is this: because of the nature of the leak only in cold weather, is there something else i need to be looking for or is it as simple as replacing the injector and calling it a day?

TIA.

Paul

New seals

It sounds like you just need to replace the seals. The whole kit is about 5 bucks at NAPA. You can use some good ol' vaseline (petroleum jelly) to lube the seals so they seat better. I would only change the injector if there is a performance issue as they are about 85 dollars each.

Changing the orings will likley be a temporary fix, as the Renix injectors are known for leaking at the main body seam after a while. I've had to change all six on my 87 and my 89, and I have the fuel rail from my (now down pending refit) 87 standing by for when I lose the injectors in my 88.

A little digging around on the "strokers" egroup can give information for what other injectors will fit, as the direct aftermarket replacement units are about $60 each, while V8 sets can be had for as little as $200 or so. I think a lot of SBChevvy injectors will cooperate, but you'll want to check (I may have all that in a notebook somewhere as well...)

Oh - don't use Vaseline for hte injector orings. Draw a small cupful of gasoline when you depressurise the fuel rail, and soak them all in that. It works better. If you absolutely feel a need to lubricate things, a touch of assembly lube works better anyhow, and will dissolve when the fuel hits it (gasoline + Vaseline = napalm...)

5-90

injectors

It is my understanding that when you change injectors all need to be changed at the same time.
Heard this thru the "rumor mill",so I'm not entirely 100%sure if this is true or not.
There are also several different injectors out there that will work,and some are a little more money pocket friendly.

Napalm?

You guys come up with some good ones. There are oxidizers in napalm that cause it to burn hotter and continue to burn. Vaseline is not an oxidizer. Gasoline + vaseline = greasy gasoline. Take it from a technician (and 2 years of chem engineering to boot) that vaseline is compatible with all fuel system components as it's made from PETROLEUM. I stand by my original assessment. If its a leak you're looking for try the seals first as it's cheaper to replace those than the injectors and troubleshoots your leaking problem. If you find the injectors are the problem then come back and we'll help you find some. As an aside there are other injectors that many here use besides OEM.

"Napalm," generically speaking, is simply a jellified form of gasoline (or other volatile fuel) - essentially fuel mixed with a plasticiser. Commercial napalm has the addition of (I think usually phosphorous) compounds as oxidisers and additional fuels, but it can be something as simple as gasoline mixed iwth liquid soap or even blood plasma (yes, they work.) Where'd I learn that? Useful little course at Ft. Benning called "Kitchen Table Demolitions." (BTW - you CAN make a primitive napalm with gasoline, Vaseline, and an additional component to make it a little more effective - but I shan't say what. There's enough ways to kill yourself online already!)

I guess I'm a little concerned, since Vaseline can be used as a plasticiser for other volatiles to make highly primitive - yet still effective - forms of plastic explosive. I prefer to use assembly lube anyhow, since it seems to dissolve more readily and is more lubricious (is that the word?) than Vaseline in the first place.

On a related note - I have changed injectors singly, but only when the replacement injector is the EXACT SAME rating as the one it is replacing. But, since you've got everything torn to bits (and you're probably replacing the old usit because it IS old) you really should replace them all at once anyhow.

I also brought up the point about replacing injectors completely since it is probably safe to assume they are OEM or close to it, and the OEM ones DO leak at the body seal (I've been thru this a couple times myself already!) The Renix units are known for that, the HO units tend to hold up a litle better...

5-90

The old injectors can also leak at the rubber grommet where the wires enter. This can be pretty hard to track, too, because the seepage evaporates so fast.

go to www.fiveomotorsport.com you need ford/bosch injectors. these guys have fantastic prices. dollar for dollar, this has been the best improvement I've made on my '90 4.0 and they come with o-rings

I put some Ford "yellow" top 19# 4 port injectors (finer spray pattern) in my 90 Cherokee. They are used in their 5.0 engines. Throttle response is smoother off idle and fuel mileage increased about .75 mpg.
Got them free at an engine core yard, used NAPA "o" rings.
You can also find them on eBay.

Paul,

I changed my injectors 2 years ago in my 88 XJ for safety. I had read multiple posts about the Benidx injectors leaking between the metal body and the plastic portion of the Renix 4.0 (87-90).

I have the EFI manual from AMC/JEEP for the engine. It talks about have to replace the quick connect coupling when you disconnect the line from the fuel rail. It is those plastic ears sticking out. You squeeze the ears then pull apart. Then use a paper clip to pick out the 2 o-rings and the spacer. Then install a new "coupling renewal kit". You get the kit at the dealer and they run around $15. I used 2 kits when I changed my injectors.

I was not bold enough to change to a different injector so I searched the on-line web sites and found the best price for stock replacement injectors was at www.rockauto.com. I installed 6 "Standard" brand injectors. If you want to go with the mustang 5.0 injectors why not contact one of these injector rebuilders, tell them what you plan on doing. They may bring up something. A guy at work has a relative who does rebuilds. The relative was telling the guy that not all injectors are not interchangable due to the resistance of the coil. I have read the injector swap lots of times on here but I would check out the full interchangability before you do install alternate injectors.

The EFI manual said you should get 13 O-rings in the kit from the dealer, 12 are used on the injectors, the 13th is used on the pressure regulator. You remove the two screws attaching the regulator, pull out the regulator, change O-ring, and re install.

With the age of my XJ I decided to spend the $65 and buy a new regulator since it was just those two screws that kept it on after the fuel rail was removed.

I used motor oil on my o-rings but my dealer mechanic said later petrolium Jelly, Vasoline is a brand name of it, would work just fine. He said about anything to give a little lube as you slide it in.

I found removing the clip on the electrical connector make removal easier, I am talking the clip that is about the same size wire as a paper clip. Once you have the connector off, reinstall the clip. Then when you reconnect the harness to the new injector it will just "click" on.

Also mark you electrical wires so you do not hook them back up in the wrong order. I just used colored electrical tape and marked the wire the connected to the more "forward" injector of the two. You will notice those pigtails come out of the harness is pairs.

You will need to bleed down the fuel pressure before you start. Just press the schrader valve on the side of the fuel rail. Also if you can work on a cold engine, one that sat overnight just to prevent any chance of fire.

Hope that helps, I am sure I left something out.

I've been replacing injectors as they fail. 2 of the 3 leaked where the metal body meets the plastic and one leaked at the connector. I used OEM replacement parts.... by that I mean parts that are designed to meet OEM specs. They aren't the same brand but the engine runs perfectly. MPG is great... holding steady in the 20 range. My mechanic says just replace them as they fail. He claims the repeated heating and cooling of the injectors between drives eventually causes the leaks.