SOLVED Starting problem need some advice please 99 Limited

[mfitz725]

Started her up this afternoon and as was the usual didn't quite start on the first try but cranked immediately on the second try. Ran ok, if its cold it stumbles some until warmed up and I'm pretty sure it needs upper/lower intake gaskets as I'm at 175000 and haven't been done to my knowledge. However, I drove into town far enough for it to reach operating temp. Was in a store for about 10 min. Would not restart. I tried numerous times, 12-20, and eventually called a ride assuming I would need a tow. But, not to be deterred I tried another 4,5,6 times and it finally started. Went home would not restart as soon as I turned it off. It's been sitting for 6 hrs now completely cold and it started immediately on the first try and ran smooth. (it's 58 degrees out)

Now it frequently takes 2-3 times to restart when warm. Once in a blue moon I can be driving and hit the accel and it has basically no response or stumbles bad for quite a number or seconds but recovers and doesn't act up for quite a while. I had concerns that maybe it might need a fuel pump as I looked thru some posts on here and already have one just in cased I just don't know how to check it. I don't think I have the necessary equip.

So what do you guys think. Would the gaskets cause this kind of restart problem or should I try to focus on the pump. Or I'm I barking up the wrong tree. I'll have to get it somewhere probably to have pressures checked unless tools I need are relatively inexpensive. Please give me some feedback based on your expertise dealing with these things.

Thanks

 

[koda2000]

Regarding not starting - My guess (and it's just a guess because you have done no diagnostics) would be fuel pump.

You don't say which V6 engine you have, but I assume it's a SOHC. You likely need upper/lower intake gaskets replaced for rough running when cold.

 

[Mbrooks420]

Does it always start easy when totally cold?

First guess is fuel pump, second is coolant temperature sensor.

 

[donalds]

Does it always start easy when totally cold?

First guess is fuel pump, second is coolant temperature sensor.

Exactly what I was gonna say I leaning towards coolant temperature sensor

 

[Mbrooks420]

This plagued my last 5.0. Took me forever to figure it out. It was burned up welding on the body.

 

[mfitz725]

Regarding not starting - My guess (and it's just a guess because you have done no diagnostics) would be fuel pump.

You don't say which V6 engine you have, but I assume it's a SOHC. You likely need upper/lower intake gaskets replaced for rough running when cold.

Yes, sorry it is the SOHC. I ran the diagnostic and got PO171 too lean on bank 1 (pending failure expected...suspect low fuel pressure). All other codes were not related to this issue

That would possible make the pump suspect but based on the 2 responses below I'll try the temp sensor first since that's a lot less effort than dropping the fuel tank.

Thank you for responding I'll let you know what happens tomorrow.

 

[mfitz725]

Does it always start easy when totally cold?

First guess is fuel pump, second is coolant temperature sensor.

Yes it starts very easily cold. Thanks for the input. I'll try the sensor first. I say that because trying to switch it on several times in a row to let the pump to prime the system, so to speak. Once it cools down again it starts.

 

[Mbrooks420]

When my temp sensor was bad I’d roll the motor for 3 seconds, pause a few seconds, till it over again for 3 seconds, pause, and then crank it until it started. Almost always started on the third try.

It can be tested with an ohm meter I’m sure.

 

[mfitz725]

Well, the bad news is I went to work on it and the ambient temp was in the low 70's and it wouldn't start. So I replaced the temp sensor and put in a new thermostat while I was in there.

The GOOD NEWS is after replacing that sensor it started on the first try also. I let it warm up and the restart worked on the first try. So I think I've got the problem licked.

 

[Mbrooks420]

Boom, hope it was the issue.

 

[mfitz725]

Well the next day it wouldn't start again. I was then thinking fuel pump. Ck'd the relay and then got someone to switch ignition on while I tried to hear fuel pump. Didn't hear it. While searching the forum for other ideas came across posting about PATS problems.Got the spare key out and it started first try, tried regular key and no start. Tried spare again, ok. Tried regular and it turned over 5-8 seconds but did start. Went out next morning and both keys work. WTF

When all this started I pulled codes and saw I got this: B1602 - PATS Received Invalid Format of Key Code from Ignition Transponder

I took this as some kind of fluke as I have used the same key since 2017 when I got the X and it has up until now always started.

I guess I'll just wait and see if it doesn't start again sometime and keep the spare with me and see what happens.