My 1978 280 Z car

[argniest]

I personally wouldn't see any use to an in-dash digital fuel pressure gauge. Fuel pressure goes up and down with engine vacuum, so unless you have both gauges going (fuel pressure and engine vacuum) and are very quick with mental mathematics, it's not really going to tell you much.

Well :-) I was just thinking that if there was a *problem* with the fuel pump, and it was changing my fuel pressure in a somewhat abnormal manner, that having a digital readout in the cockpit would allow me to see what was going on, and when it happened. One of the problems that my Z car just starting exhibiting was this situation where it seems to buck, or lurch, and then pickup speed again, and then do the buck or lurch again. It has only happened 4 times now on three test drives. but it never did that over a period of 4 months when I got to drive it in the warmer months. It was 5 to 10 degrees when this happened each time. And also, its also died two times as I mentioned. The problems seem related to me.

A mechanic suggested to me that he saw these problems happen before and he fixed them by replacing the fuel pump. Of course he diagnosed the problem before actually replacing the fuel pump :-). He had a voltmeter (I think he said) and fuel pressure guage on the fuel line, and had the car running up on a hoist in his shop. When the problem happened he immediately looked at the fuel pressure guage and voltmeter, and said it told him it was the fuel pressure. Once he replaced the fuel pump the car never had those problems again. And the car has been driven for years after that with no occurance.

He told me some other stories about other cars he fixed, with similar problems.

Sooooooooo :-) I was merely thinking that if I had a way to monitor it from my car, while I was driving, it might help me see whats going on. I suppose they dont even make something like that anyway...as an addon for an old 78 car like mine.

Im just freaking out that my car is doing this now, for no apparent reason. And now I cannot even think about driving it anywhere for fear of it dying in a bad place. I guess I can drive it on side roads to see if it happens again. I have been cleaning some of the connectors in the car, and today I am getting that deoxit D5 stuff. So I can shoot that stuff in all the connectors that are easy for me to see.

[FastWoman]

Well, if you simply need to diagnose a problem possibly relating to fuel pressure while you're driving, you could always run a long fuel hose from that T-fitting, out through your cracked hood, and into your window. If you need to close up the car, just roll up the hose and tuck it back under the hood. Theoretically you should only use fuel injection hose, which is about $4/ft, but I think you could get away with regular fuel hose for maybe $1.60/ft just for the testing.

If your fuel pressure cuts out, remember that the problem could be electrical! I suppose you could also run some wire from your fuel pump terminals to a light in the cockpit. If the light flickers or goes out, then you're losing power to your pump.

FAIW, there are two very large connectors on the cockpit side of the firewall on the righthand side. The fuel pump supply runs through one of those connectors. Mine was charred and melty (inadequate connector), and my fuel pump kept going out because of failure of that connection. I finally had to snip the wire out of that connector and connect with a bullet connector. Problem solved.

[argniest]

Well, if you simply need to diagnose a problem possibly relating to fuel pressure while you're driving, you could always run a long fuel hose from that T-fitting, out through your cracked hood, and into your window. If you need to close up the car, just roll up the hose and tuck it back under the hood. Theoretically you should only use fuel injection hose, which is about $4/ft, but I think you could get away with regular fuel hose for maybe $1.60/ft just for the testing.

Another mechanic told me about that, but it scrared the hell out of me thinking about having the fuel hose running all the way up there. I wont do that. Too chicken I guess. Which is what got me thinking about buying a fuel pressure guage that had a digital read out that I could put in the cockpit. That would be safe...and fun to watch the fuel pressure while I was driving so I can understand what is going on with it.

If your fuel pressure cuts out, remember that the problem could be electrical! I suppose you could also run some wire from your fuel pump terminals to a light in the cockpit. If the light flickers or goes out, then you're losing power to your pump.

Yes, I was thinking about temporarily hard wiring a simple test light (like one that that has an alligator clip on it), into the green power wire, that is found under the carpet on the passenger side of the car, right behind the seat. I havent figured out the best way to do that without destroying the two bullet conenctors on those two wires that power/ground the fuel pump. I basically want to make a T connector, so I can leave the existing bullet connectors alone, and then also add my test light into the circuit. That way, if/when the car dies and wont start, I could see if the test light is on or off. And combined with the ability to see my fuel pressure would help me diagnose if the fuel pump itself was not putting out pressure (for any reason), or if the electrical connections feeding back to the fuel pump are having issues.

FAIW, there are two very large connectors on the cockpit side of the firewall on the righthand side. The fuel pump supply runs through one of those connectors. Mine was charred and melty (inadequate connector), and my fuel pump kept going out because of failure of that connection. I finally had to snip the wire out of that connector and connect with a bullet connector. Problem solved.

I have that color coded wiring diagram, so I will look for those that you mentioned. And see what condition they appear to be in.

man on man....am I in for a long long journey. So many things to check out, cleanup, work on, etc BOY I was niaeve to think my car wouldnt end up having these kind of problems.

Edited January 12, 2011 by argniest

[FastWoman]

If I were you, I'd monitor the voltage right at the fuel pump. Put a ring connector at the end of a long wire, and connect that to the (+) terminal of the fuel pump. Run that into the cockpit, possibly around the back of the car and under the hatch door. Then wire a test light between that wire and some ground point in the cockpit area.

Better still, just verify all of the wiring. It's not that hard.

FAIW, the AFM has a fuel pump cutoff switch. Some people have trouble with that cutting out at low idle. It takes a bit of adjusting to stop it from happening.

Regarding the fuel gauge, you would really do a permanent installation of another instrument just to debug your engine? That doesn't make any sense. There's nothing dangerous about running a fuel hose, especially if you secure it with a few zip ties. (Just be sure to bleed the air out of it, first, though, or your fuel pressure regulation will get sort of sloppy!) If it worries you that much, just pay the $4/ft for the fuel injection grade hose. It will still save you money over the permanent installation of an expensive gauge you don't need.

Edited January 12, 2011 by FastWoman

[Jennys280Z]

CAn you take a look at this list, and tell me which one you are talking about? I see D5S D100S, etc

http://www.parts-express.com/wizards/searchResults.cfm?FTR=deoxit&search_type=main&WebPage_ID=3&searchFilter=deoxit

Also, I think this is what you are talking about. And its the only place in my area that says they have it.

http://www.guitarcenter.com/CAIG-DeoxIT-D5S-6-Spray--Contact-Cleaner---Rejuvenator--5-oz--101175859-i1134929.gc

I saw this special kit with more stuff in it??? Think this would be useful in my cleaning endeavors? Or just the D5 product above.

http://www.guitarcenter.com/CAIG-Audio-Survival-Kit-429166-i1134928.gc

This will do it:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=341-200

It's fun to use. Your connectors "sizzle" for a second after spraying it on.

D5 worked great for me on the Z. I use it around the house too. It's fixed weak and intermittent connections on my Z, assured good clean connections on my FI, and fixed items in my household, like my kitchen timer, which was outputting garbage data even on a fresh battery till it got the Deoxit. Now it's been running perfectly for months.

[Jennys280Z]

Also, your electrical connectors are very fragile so be extra delicate with them. That's more important than losing a clip. I should have mentioned that first thing.

[argniest]

If I were you, I'd monitor the voltage right at the fuel pump. Put a ring connector at the end of a long wire, and connect that to the (+) terminal of the fuel pump. Run that into the cockpit, possibly around the back of the car and under the hatch door. Then wire a test light between that wire and some ground point in the cockpit area.

Yes I like that idea the best. That is what I will do. Then I am connected directly to fuel pump. I can always connect somewhere else, if its a wiring problem in the car somewhere.

Better still, just verify all of the wiring. It's not that hard.

Ahhhh man you make me laugh its not that hard huh. Welllllllll, I have never done anything like this before to a car. So it is very intimidating. Now, I am a computer builder, software engineer, audio/visual maga freak, and geek toy researcher and user...so I do have some skills with hardware. But not with a car, and that is 33 years to boot. Everything is pretty fragile. Im scared about totally f-ing everything up like a snowball effect! Thankfully my relative who restores cars, can eventually bail me out. But that will be expensive. I really really do want to learn all this stuff. In such a fast paced world and fast paced career I am in, I am not used to things taking a long time, like I know this will. So I am combating against that now too.

FAIW, the AFM has a fuel pump cutoff switch. Some people have trouble with that cutting out at low idle. It takes a bit of adjusting to stop it from happening.

What do you adjust? where? The thing is that this (the car dying) happened with the old AFM and the new one which I installed one day after the car died the first time on Jan 1st of this year. So that tells me it must not have anything to do with the AFM...right? So problem must be elsewhere I am assuming. because this fuel pump cutoff switch I am assuming is inside the AFM. If not, then please correct me. Thanks!!!!

Regarding the fuel gauge, you would really do a permanent installation of another instrument just to debug your engine? That doesn't make any sense. There's nothing dangerous about running a fuel hose, especially if you secure it with a few zip ties. (Just be sure to bleed the air out of it, first, though, or your fuel pressure regulation will get sort of sloppy!) If it worries you that much, just pay the $4/ft for the fuel injection grade hose. It will still save you money over the permanent installation of an expensive gauge you don't need.

Well I wasnt really meaning that my digital fuel pressure guage would be permanent. I only meant to have it installed (assuming it even exists) during the time I am having problems then I would take it out.

THANKS AGAIN!!!! Youre awesome!

[argniest]

Also, your electrical connectors are very fragile so be extra delicate with them. That's more important than losing a clip. I should have mentioned that first thing.

And that is exactly what scares the bejesus out of me. I am good with computer hardware, any a/v equipment, and numerous tech toys for 20+ years now. But a 33 year old car, where everything is old and interconnected and fragile. I jsut have feeling this is going to end badly and I will end up calling in the calvery. But hopefully if I am very careful and patient, and just do a few things at a time, then retest everything in the car....I can slowly move through all my connections and clean them up.

I have looked in a few of them under the hood, and I see a little green crusty stuff in there. So I just used a little mini screw driver to clean them up for now. And today thankfully I found some deoxit D5 at guitar center. So I can start using that too.

[argniest]

Well tonight I let the car idle, to listen for another noise I have noticed it making since the wintertime blues have struck us. Well, the interesting thing is that both times I have idled the car until it got good and warm, it was making this alternating noise under the hood. I couldnt pinpoint where it is coming from. But it almost sounds like a whoosing sound, or water moving and then not moving, and then moving and not moving....but once car got warmed up, it never made the sound. And I know for sure I never heard it in the summer or fall time. So its definately doing something different when its warming up now in the winter time, that must not be happening in the warmer temps. When the noise happens, it keeps making the noise for a few seconds, then stops, then starts again for a second, then off, then on for a few seconds and off. And it really seemed to me that the warmer the car got the less it started happening. Until all of a sudden you just dont hear it anymore. hmmmmmmmmmmmmmmmm

I will listen for it each time I warm up the car and or drive it, assuming I get gutsy enough to do that around my neighboorhood at least (after snow melts too).

More interesting, is that once it got warmed up I decided to turn on my lights and immediately they came on right away. I was like what theeeeeeeeeeeee heck???? So I turned them on and off a bunch of times, and they always worked. And I left them on after I turned off the car and pulled back into garage. And they stayed on. So what is up with that????? I wonder. I mean I am glad they worked, but this is just crazy stuff I didnt expect them to work....because when it was still warming up, guess what, they didnt work. Only when engine was good and warm.

[FastWoman]

Argneist, if you build computers, you can work on the Z. The connectors inside computers are much finer and more delicate. Nothing will fall apart, perhaps except for some of the fuel injection connectors in the engine compartment. However, you can easily replace those (see prior link in this thread). I think you'll do fine, once you get over your fear of the car. (It's pretty hard to blow anything up. If you want to be ultra-conservative, just pull the negative cable off the battery whenever you do electrical work. Then it will be near impossible to blow anything up.)

The intermittent problem you describe in your last post sounds like classic dirty/corroded/loose electrical connections and/or dirty/corroded switches. Think of it as a rnd() function in your wiring.

If you can find a digital fuel gauge with a long cable, go for it. However, there's a lot to be said for just laying the thing in the passenger seat, rather than screwing it to your dash.

Personally, though, I really doubt your fuel pump is bad. Usually anything with an electric motor either works, or it quits. There's not much inbetween. If the pump operates correctly in the driveway, it'll almost certainly operate correctly when you're driving. The electrical connections are more likely the culprit (assuming you have fuel pressure problems at all).

[Jennys280Z]

And that is exactly what scares the bejesus out of me. I am good with computer hardware, any a/v equipment, and numerous tech toys for 20+ years now. But a 33 year old car, where everything is old and interconnected and fragile. I jsut have feeling this is going to end badly and I will end up calling in the calvery. But hopefully if I am very careful and patient, and just do a few things at a time, then retest everything in the car....I can slowly move through all my connections and clean them up.

I have looked in a few of them under the hood, and I see a little green crusty stuff in there. So I just used a little mini screw driver to clean them up for now. And today thankfully I found some deoxit D5 at guitar center. So I can start using that too.

Here are some good cleaning instructions you will want to reference before proceeding:

http://www.atlanticz.ca/zclub/techtips/electricalconnections/index.html

I had a lot of green oxi-crust in the connectors near the front of the engine including @ the #1 and #2 fuel injectors. The C-clips on the fuel injectors are a lot easier to work with than the G-clips found elsewhere.

[argniest]

This a great place online. Thanks so much for your help!