79 Seville hard start issue

[Gene Beaird]

Thought I'd post this up to see if I can get some suggestions to point me in the right direction to look at. 

I'm going over our recently-acquired 79 Seville, fixing the little things that just aren't right.  One of the things I've noticed that it is somewhat hard to start when cold.  I'm talking southeast Texas cold, here, probably 50's-60's F, so not too bad for some of you.  Anyway, when I go to start it, I can turn the key on and hear the fuel pump spin up and stop, as expected (unfortunately, I can do this with the door open, and the 'keys are in the ignition' alarm doesn't go off....  another thing to fix).  I turn the engine over and it almost starts, but doesn't. 

If I repeat this process 4 times, that is, turn key off, then on, wait for pump to quit spinning, then turn key to start, the engine will finally start.  It then runs for about 5-10 seconds and then dies.  Usually, the 5th or 6th time using this process, the engine will stay running, starting at an expected high idle, and idling down as it runs, although never down to an RPM I'd expect to see.  Note that I have yet to touch the accelerator during this process.

After it warms, it starts with no issues first time.  An additional point to note is that the engine, although I have yet to hear it ping, smells like it's running lean.  You know that acrid, burn-your-nose smell you get when a gasoline engine is running lean?  That's it. 

Any thoughts?  I'm thinking possibly a bad or dead in-tank pump?  So far, all the vacuum hoses look good and attached, although I can't get the HVAC to work properly except on de-ice. 

Thanks for the info! 

Regards,

[waterzap]

Could be one of the temp sensors. Check those first, easy to check.
The Air temp sensor and coolant sensor. They dont have much effect when the car is warm. Test them. Car off should read around 1000 ohms. I have a sheet that specifies 600-1600 ohms

[waterzap]

I got this checklist with a fuel injector diagnosis kit. Some of these test you can do without the kit. Probably a good idea to measure the things they have on the list

[Gene Beaird]

Thanks, Waldo.  So the coolant temp sensors make the most difference when cold?  Wow.

Okay.  Heading out to the shop tonight. 

[waterzap]

Correct. They add enrichment when the engine is cold.
In the manual, the number one problem for hard starting is one of the temp sensors, and in brackets they say, starts ok hot.

[Gene Beaird]

Looks like the one in the water jacket doesn't even move the ohm meter.  The other one reads about 965 ohms. 

Looks like I have more parts to buy! 

[bcroe]

They are interchangeable.  The one in the water jacket is far more important,
put the good one there as a quick fix.  Get 2, they fail a lot. 

You might try pumping it a few times before cranking to get some extra starting
gas; you will hear the injectors clicking.    Bruce Roe

[Gene Beaird]

Huh.  I didn't know these early FI systems worked like a carb.  I did the start w/o using the accelerator pedal as a test to see how much it would take to get it started, if at all, to try to troubleshoot the issue.  FI systems, IMHO, should just turn over a couple of times an light. 

[bcroe]

The later digital EFIs are much more sophisticated.  The 76-79 systems were
designed before microprocessors were available.  Bruce Roe

[Gene Beaird]

Two switches have been ordered from MTS.  Hopefully that'll fix the issue, and I can move on to other things.  I think getting the HVAC working properly again will be next.

[surfexplorer]

Hello Everyone,

I have a 1978 Seville that was exhibiting the same exact hard cold starting problem as described in this thread.  I checked both the coolant and AIR EFI sensors ans found the Air sensor was reading ~1000 ohms and the Coolant sensor was reading 1600 ohms.  After swapping both sensors my car for the first time in many weeks cold started without any issues.  The car seems to run just fine with the faulty sensor moved to read Air temp but I will look to replace anyways in the near future. 

Appreciate the help- just joined today to post this response.

[79 Eldorado]

Hello and welcome to the forum. I was the person answering your questions on eBay ! Happy to see you found the forum.

Scott
"punched455"

[surfexplorer]

Its a small world- Thanks again.

[The Tassie Devil(le)]

G'day RJ,

You have an email from the Moderators that requires your attention.

It was sent on the 1st May.

Thanks,

Bruce.