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914World.com _ 914World Garage _ 73 2.0, wont start when warm

Posted by: drgchapman Mar 7 2005, 11:32 PM

We have a 73 2.0, signal orange,box stock, rebuilt motor this winter. Pretty clean little car. We are second owners. Car has run great until this week.......OK, I've heard of the vapor lock warm start thing. But we live in Portland!...and it's February! For the past three days the temp has been in the 60's, hit 70 today. Saturday, drove teener to lunch, had lunch, starts after much cajoling. Then today, strands Pamela in Beaverton for about an hour. She finally gets it started. Car tuns over just fine, won't fire. Spit, cough, whirrr.......

Do we have a vapor problem? In Portland, less than 70 degrees?

Gary

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Posted by: trekkor Mar 7 2005, 11:45 PM

No whir, huh?

You turn the key on and no fuel pump momentary hum?

KT

Posted by: SirAndy Mar 7 2005, 11:54 PM

QUOTE (drgchapman @ Mar 7 2005, 09:32 PM)
Do we have a vapor problem? In Portland, less than 70 degrees?

no. most certainly not ...

sounds more like a electrical problem to me. take one injector out and hold it over a jar while you crank it over. if it sprays, yer fuel delivery is fine.

next (after the injector is back in place!) take out a sparkplug and crank her over and see if you got spark.

obviously, all this while she's warm and not starting. check the wire and connectors to the CHT. make sure there's nothing lose there. make sure the CHT itself is not lose.

post a pic of your engine comp!
Andy

Posted by: drgchapman Mar 7 2005, 11:55 PM

Yeah, the fuel pump runs when key turned on for about 2-3 seconds. Starts great cold, runs a little rough until warmed up.

Check your tire thread, trading some experience here.....this is cool!

Gary

Posted by: gregrobbins Mar 7 2005, 11:55 PM

I am having a similar problem with my '73 1.7L. Here is some information I got from Slits
QUOTE
Hi Greg,

More than likely, it's an electrical problem in a couple of areas:

Voltage drop to the coil...due to old wiring or a problem in the ignition switch itself, the starter is drawing a lot of amps and decreasing the voltage to the coil below 10 volts when hot. They make a kit that consists of an external solenoid to work around this problem.

You could start by cleaning all the contacts from the battery thru the system (when you have nothing else to do)

You could change the back part of the ignition switch..there are contacts in there that get burned from electrical flashing over time. Usually the are cracked and some portions don't make contact real well.

It is possible that the starter itself could be a problem in that the solenoid contacts are burned or the field windings have to high a resistance.

Start with the easiest..cleaning wiring contacts (including the battery ground to the body).

Also, if the battery cables are old and corroded (inside the sheathing), this will cause a large amp draw and voltage drop in the ignition circuit.

Ain't this fun?

Also, here is a link to my post from Saturday
http://www.914world.com/bbs2/index.php?act=ST&f=2&t=26553

Posted by: Rhodes71/914 Mar 8 2005, 12:08 AM

Thought I had this problem solved with an ignition switch change out. But yesterday it was pretty warm on this side of the mountains (for March anyway) and I drove it pretty hard for about 20 min. Got home shut it off, tried to start about 5 min later and same symptoms your talking about. Turns over fine, I like the low voltage to the coil idea, think I will check that next time it happens.

I think a push start will work in some cases in a pinch if you can't wait. I think I waited about 30 min and it started right up.

Posted by: skline Mar 8 2005, 01:12 AM

Wow, I cant believe Slits didnt tell you how to fix it. I had this same problem when we went on the baja run. It was the head temp sensor. He knew it right off the bat. Never had the problem again.

Posted by: Rhodes71/914 Mar 8 2005, 01:33 AM

QUOTE (skline @ Mar 7 2005, 11:12 PM)
Wow, I cant believe Slits didnt tell you how to fix it. I had this same problem when we went on the baja run. It was the head temp sensor. He knew it right off the bat. Never had the problem again.

Why does it always come back to the CHT sensor on the FI system. Mine is new but that doesn't really mean anything.

Posted by: Cap'n Krusty Mar 8 2005, 01:48 AM

The CHT sensor is out of the circuit once the engine is at operating temps, as long as it provides a ground. Over the 33 years in the business, I may have sold 10, and some of those were on complete rebuilds, just 'cause I could sell 'em. New 2 litre cars required a steady half throttle to start warm. An "electronic lie", we were told at school. The ECU, simple as it is, couldn't prioritize the inputs, and wouldn't provide the necessary mixture to fire. Longish crank times were the norm. The Cap'n

Posted by: drgchapman Mar 8 2005, 09:04 AM

Thanks for the input guys. Won't be able to apply for a couple of weeks, as we are out of town. I'll try the coil first, then the CHT?

Gary

Posted by: SLITS Mar 8 2005, 01:56 PM

Now with all of this said, I was having a conversation with the owner of Fuel Injection Corporation, who stated he cut his teeth on D-Jet and was able to diagnose any problem, yada yada yada....anyway,

He said that if the CHT was suspect to take a paper clip and hook it inline with the CHT (I assume this means you have a good electrical circuit). This must emulate the resistance it is supposed to give and it will solve the problem.

No, I haven't had an opportunity to try it yet

PS: he didn't state what size paper clip.

Posted by: Jeffs9146 Mar 8 2005, 02:31 PM

QUOTE
obviously, all this while she's warm and not starting. check the wire and connectors to the CHT. make sure there's nothing lose there. make sure the CHT itself is not lose.

My threads on the CHT were messed up and that would happen every time it warmed up! I repaired the threads and put a new CHT and it ran like a champ!!

Start with that then check the coil!

Jeff

Posted by: mikerose Mar 8 2005, 02:41 PM

I had a 1.8 that from time to time this would happen. It drove me nut's then one day mueller came over and we went over everthing and l that's when we found the bugger
Rember mueller? just the CHT all this time

Mike

Posted by: drgchapman Mar 8 2005, 03:02 PM

OK I"ll try the CHT first then the coil.

Thanks to all of you!

See ya in about three weeks.

Gary out of country

Posted by: skline Mar 8 2005, 03:11 PM

QUOTE (SLITS @ Mar 8 2005, 11:56 AM)
He said that if the CHT was suspect to take a paper clip and hook it inline with the CHT (I assume this means you have a good electrical circuit). This must emulate the resistance it is supposed to give and it will solve the problem.

No, I haven't had an opportunity to try it yet

PS: he didn't state what size paper clip.

Probably a 4 or 5 amp.

Posted by: Rhodes71/914 Mar 12 2005, 04:42 PM

Could the points in the dizzy have an affect when starting a warm engine?

Mine did not have enough gap, I've since changed the gap so my dwell is correct and have not had a warm start problem since.

Posted by: Bruce Allert Mar 12 2005, 05:01 PM

QUOTE (SLITS @ Mar 8 2005, 12:56 PM)

He said that if the CHT was suspect to take a paper clip and hook it inline with the CHT

inline from the CHT to what?

........b

Posted by: redshift Mar 12 2005, 05:31 PM

Wire...

------male connector-paperclip-female connector------CHT.

M

Posted by: anthony Mar 12 2005, 05:47 PM

Gary, when the car won't start, is the starter turning the engine over? Or, is it "click" and the starter is dead?

If the starter is turning over try what the Captain said and give it more than half throttle. The manual for my '74 2.0 actually said to put the accelerator to the floor when starting hot.

If it's just "click" and the starter doesn't turn over then it's probably an old starter or any of the other probable causes (ignition switch, cht, etc.).

Installing a relay kit to the starter might also help.

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