1992 Ford Thunderbird Hard start when engine is at operatin

RYANMANCL

MEMBER
1992 FORD THUNDERBIRD
6 CYL
2WD
AUTOMATIC
90,000 MILES

I have a 92 thunderbird sc. It starts up great when the engine is cold, but when it is hot more often than not It has a hard time starting, sometimes when its turning over it stops dead for a second then continues turning over, sometimes it turns over slowly, and sometimes it turns over for a long period of time before firing. Usually all those things happen in the same start. I have replaced a cam sensor, dis module, and the battery is good, the starter has also been repalced twice. It almost feels as if it is trying to fire the wrong cylinder when starting up and thats what stops the starter. I was thinking eithe a crank sensor or a coolant temp sensor next, any ideas?

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Battery good and Starter replaced 2X-double check the battery connection make sure its cleaned and tight. Test the starter relay-Everything okay on these 3 items-Check the ignition timing then come on back. Are you experiencing overheating? Engine oil level is it okay-

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Thursday, May 1st, 2008 AT 1:38 PM

RYANMANCL

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7 POSTS

The battery connections are good, I swiched the relay with another that matched and I had the same issues. Oil is good, teh temperature on my guage does move while im driving but it never leaves the normal range. As far as timing I can't check that myself, just moved and im limited on tools. But it is dis system. And it is an intermittent problem that does seem to be getting progressively worse.

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Thursday, May 1st, 2008 AT 1:55 PM

RASMATAZ

MECHANIC
75,992 POSTS

Are you still having problems cranking engine over? If not and engine refuses to start-try doing below

Get a carb cleaner and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light.

Fuel pump and Injector/s checks out-start checking the ignition system-power to coil, coil/s itself, distributor pick-up, control module, Cam and Crankshaft sensors.

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time

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Thursday, May 1st, 2008 AT 3:08 PM

RYANMANCL

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7 POSTS

I have never had a no start. Just a hard start, either a long crank or a start that feels very similar to a starter dragging very heavily. Could either a crank sensor or a coolant temp switch cause the engine to fire at an incorrect time, especially with it only happening when the engine is at operating temp?

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Thursday, May 1st, 2008 AT 4:23 PM

RASMATAZ

MECHANIC
75,992 POSTS

You get your cold fuel enrichment with the coolant temperature sensor during initial start up and for CPS it sends data to the computer is to the position of the pistons and engine rpm. Check the CPS and wiring.

Further you might want to check the actual fuel pressure. And give us some readings. So we can evaluate-