Intermittent Loss Of Power-1972 240Z Stock

[madkaw]

Replace the coil for sure. Cheap and you get to cross it off the list. When coils act up its usually under loaded conditions.

[240260280z]

This is what came out of my friend's tank who suffered from debris causing his car to randomly die..... just a few flakes.

 

Try not to be deceived.

 

When your car dies, check immediately for spark and also check for fuel in the bowls. 

 

 

[AWAUDIO]

@blue  Problem is she doesn't die.  Never has.  Always lets me limp home bucking and lurching.  Sitting in the driveway she idles perfectly and will even accelerate, with a slight hiccup, but she runs.  Under load has no power.  And as I mentioned, yesterday she just started like she wanted to go go go (usually I have to encourage her till she's warmed up).  But I mean she was just screaming with lottsa power.  When I last shut her off she was as described above. So I have a new coil arriving in a few hours and a fuel pressure gauge coming Sunday (I still can't figure out how Amazon can ship for free and deliver a $30 item on a Sunday).  So I'll put in the new coil, install pressure gauge and run her until she has her hissy fit.  Two things I did notice when she ran yesterday: one, the coil got very hot to the touch  and the dropping resistor got too hot to touch.  But again she was running fine.  As for tank debris, I was so hoping it was something like that.  But after draining the tank dry, into a funnel with a mesh screen, I found zero debris.  I refiltered thru a second finer mesh into another gas can and found zero debris.  My tank had fresh washer on drain plug, and appears as if it was dropped before I got it.  What I didn't do (doh) was check the fitting into the tank from the flex hose which attaches to the solid line.  I blew from the fuel filter fitting thru to flex hose disconnected from tank.  So I'll go back there if I have to.  Sometimes you just forget the obvious.  Since I might be back there, I'll pull the sending unit, but first I have to order the gasket, so that will be #3 on the "To try list"  BTW  I have all new solid fuel lines.  

 

@siteunseen Thanks for the compliments, I have put a lot of effort into keeping her straight.  I had to special order the cam lube for the points, the parts kid didn't even know what it was.  So, yep, cam lube good, and I'll throw a new rotor on, I have spare parts and it's easy. 

 

PS  here is engine right side

 

Thanks to everyone for keeping with me, all the best,  Andy

[siteunseen]

Nice pictures give me inspiration. Your pictures make me jealous. : )

[grannyknot]

That is tidy engine bay, very smart looking.

[AWAUDIO]

Ok, I've had my 18 month old Grandchild for the last three days.  Anything you want to know about diaper changing, Sesame Street, or nap schedules, I'm your guy.  Working on Z tomorrow.  Andy

[siteunseen]

I've never changed a diaper but I imagine it'd be close to M Keaton's style.

 

[AWAUDIO]

Ok guys, in the words of Sgt. Mac Elliott in the movie "Predator"  "We hit nothing"………….

 

To date I've done the following:

 

1.  New plugs , points, condenser, rotor, cap

2.  New coil with all new crimped connections at coil, dizzy, resistor

3.  Drained fuel tank, new fuel filter  ALL lines checked and tightened

4,  Checked lines from filter to tank  New lines 5 years ago

5.  Fuel pressure gauge installed at rear carb  = 3.5lbs (bounces at idle) otherwise solid stable

6.  verified voltage regulator into resistor 13.2v at idle  resistor out 10.2 v  into coil +  9.56  at coil - 6 v

 

Starts fine, idles fine, runs great for 20 minutes or so, no over heating, pulls great, then goes into stumble & lurch mode.  Will not miss or stumble except under load or hard acceleration.  It will also go into total lurch limp home mode only to clear itself and start running fine.  My next thoughts are:

 

1. per @blue  fuel lines coming off carbs for check

2. per @madkaw  go back to fuel tank for sender unit

3. per FSM check fuel pump output

 

Ok, what else?  It's either electrical or fuel.  DOH  And it's running in driveway, with no load has her purring.  So what could cause an intermittent (some days screams fine, some days not so fine), not a constant intermittent?   Temperature not a factor, NorCal. 

[240260280z]

Usually it is fuel system debris.

Once i had a points car that had no power on load. I trouble shot for fuel only to discover it was the distributor.

Edited April 22, 2015 by Blue

[madkaw]

Was the pressure checked when it was running bad?

[AWAUDIO]

@madkaw  I didn't remote mount the fuel gauge.  In driveway, in it's stumble mode/ engine revs fine and fuel gauge at rear carb reads sold 3.5 .   It's only under load on the road, after running for about 20 minutes, that she starts  acting up (except for the one time she did it cold).  I'm just reluctant to remote the gauge to the windshield, though I may have to.  Thanks for sticking with me.  AW

[AWAUDIO]

@blue  I'll put her on jack stands and hit the sender unit  (once I get a gasket).   I really wanted to find debris, but didn't on the drain or in the lines.  I'll see if I can beg, borrow, or steal an inspection scope for the tank.  BUT…what did you trouble shoot on the distributor you mentioned?  It's the intermittent aspect that has me stumped.  Did you have a dizzy with attitude?  What did you find?  

Edited April 22, 2015 by AWAUDIO