Mtnangie

Greetings,
I just got my 1975 280z. It starts every time but doesn't stay running. It almost acts like the engine is flooded...it just peters out after about a minute. The oil is full of gas -- very thin and you can smell gas just by pulling out the dipstick.
It also seems to have a vaccuum leak (maybe?) as there is gunky oily stuff in the air filter compartment. I started thinking maybe both of these issues are related -- any ideas of where to start would be appreciated.

Thanks!
Mtnangie

NismoPick

Welcome to ZDriver!

Check the connection on the AFM & CHTS first.... then check for any major vacuum leak (like a cracked or loose tube or boot).

Mtnangie

I am just learning about this car and have little prior mechanical experience. I want to troubleshoot so I am not spending a lot of dough on the figuring out part but rather on the fixing part. What's the AFM and the CHTS and where are they located? I started thinking it could be a carburetor problem but I can't figure out from the Haynes manual if this car has a carb or is fuel injected. I think it has a carburetor.
Thanks for your help!
Mtnangie

NismoPick

Wait... it's a 280z or 260z??? And a quick look under the hood should let you know if it's carb'd or injected. If it's carb's you will see twin carbs on the left (drivers side) of the motor. If it's fuel injected you will see a lot of wires and 6 fuel injectors on the intake manifold.

Here's some pics to help you out.

Carb'd:




Injected (for a turbo, but you get the idea):

Mtnangie

Oh okay, definitely fuel injected. No carbs -- I thought they might be located somewhere else than under the hood (ha!). It's a '75 280z. I spoke with one "expert" who told me it may need the carburetor rebuilt after I explained the problem to him.
Thanks again,
Mtnangie

NismoPick

Tell that "expert" he's an idiot (if he's not a relative).


So refer back to my first post... check the AFM (Air Flow Meter) and CHTS (Cylinder Head Temp Sensor) connections. Since you have a Haynes manual... look those up & you will know all... and become all powerful!

Mtnangie

Thanks i'll look into those 2 things. Yeah, I was stumped trying to find the carburetor. I thought "maybe i'm in over my head"; turns out i'm not as bad off as I thought. I'm really grateful to have found this forum as i'm quite sure i'll need all the advice I can get!

Have a great one,
Mtnangie

snwbrderphat540

gas int eh oil? thats BAD.... you should do a compression test oil and gas shouldnt be mixing, specially since gas breaks down oil and will no longer lubricate teh engine. and does teh car smoke when it does run? will it rev? and what color is teh smoke if it smokes?

Mtnangie

So far it doesn't smoke at all. Yes, it revs up and this is the only time I can keep it running -- when I rev high (obviously I won't do that anymore!). When I picked it up the guy didn't say anything about the gas/oil prob. He told me that it ran strong so, of course, we were trying to get it started. Once I got it home I started looking around. What will a compression test tell me?
Thanks!
Mtnangie

260zturbo

if its time for a rebuild

Mtnangie

Quit scaring me now...
Can't it just be something with the fuel pump or a failed regulator or something else?
I'm going to get some help next week; i'll let you know what happens.

I am also having an electrical issue -- none of the lights work (again, something else that supposedly worked up until moments before I arrived) but all of the fuses are good. Is it just a problem somewhere in the wiring system or could there be something else accounting for this?

Thanks for all of your ideas!
Mtnangie

NismoPick

You asked:


He replied:

That should explain it...


Easy way to find electrical probs... Get a multimeter / voltmeter & start checking for power.

snwbrderphat540

i needed to rebuild my dirt bike engine when the coolant started mixin with the oil, and i needed to rebuild my ninja zx6 when the gas started mixing with the oil, it would be hard to start and make run consistantly but when it did run it would be fun to ride but lacked alot of power it wouldnt even try to left in 1st gear under full throttle. it was bad news.

Mtnangie

Yeah. That would be bad news. When my trucks' coolant was mixing with the oil it was just a head gasket seal that needed to be replaced; expensive but not bad compared to a rebuild. If I would have driven it longer like that it could have warped the head -- then i would've been in trouble.
Good luck with those bikes!
Mtnangie

myxtaz

Before you run the engine any more change the oil and filter! You are going to seize the engine . If the oil is contaminated with gas the oil no longer will lubricate and you will damage all the bearings and cam. In short you will ruin the engine. Since you don't know how to work on this engine , bite the bullet and take the car to a knowledgeable mechanic . Someone that works on Zcars. You will be money ahead. A new engine is a spendy thing. Gary

Mtnangie

Thanks, yes the oil and filter are changed prior to any more starting.
Right now there's only 10 lbs pressure at the fuel pump rather than the 30 lbs it's supposed to be. He's going to check the fuel lines and change the fuel pump if necessary.
That's where i'm at right now.

Mtnangie

theramz

I think you need to have someone do a compression check. A hole in a piston would explain the large amount of gas getting down in the crank case or really bad rings. At any rate you have a potential bomb just waiting for a spark to blow the cover off. If it blows it will spray gas, oil and fire all over you and the car. If you have trouble telling the difference between carbs and FI then you need help. Be safe, Tom