B#tch to start when cold at first only TBI K5

[brans87]

I don't know much on the older TBI motors Honestly. But lately when I try to start my 87 K5 and it's cold out side 40 and below it will not start. I can get it to turn over and you can hear the newer (last couple months AC Delco fuel pump EP381 run) . Only way to get it to start is pump gas pedal when you hear it catch and when it fires up it is rich as hell!!!!!

Once it is running it will crank fine it is only after it has sat over night it seems. I do have a aftermarket temp gauge and the temp sensor on intake is aftermarket sensor.

Any ideas to try?

 

[Scribbles]

I know I' e read these motors have two temp sensors one for the gauge and one for the ECM, I'd make sure that one isn't the aftermarket one and if it were I'd swap it back to OEM. It should go without saying that you shouldn't be cracking or pumping the throttle on a TBI, just turn the key and fire.

Went back and found a thread on it
https://ck5.com/forums/threads/coolant-temp-sensor-and-flooded-tbi.288574/

 

[1-ton]

This is just a guess, but it could be the gas you are using. All gasoline comes with at least 10% Ethanol in it, and can cause problems at freezing temperatures. You could try putting in an additive called "HEET" to your gas.

 

[diesel4me]

"Dry Gas" is just methanol or isopropanol alcohol too,so adding it may make things worse if its the alcohol content causing the hard cold starts--only thing it may help is remove any water in the gas..

I would guess whatever sensor tells the ECM to "choke it" during a cold start isn't working right at low temps..if it has a fuel pressure regulator with a diaphram,it might be ruptured and letting excess fuel into the intake,that will make it start hard (flooded),and run rich until the excess gas burns off...wont hurt to check all the vacuum hoses for defects too,a vacuum leak can cause a lot of troubles like this.

 

[jekquistk5]

Or replace the CTS in the front of the intake. I haven't started my tbi truck in months. I would bet it would start on 2 or 3rd crank if I try to start it.

 

[black dawg]

Make sure the injectors aren't leaking, but does sound like a bad ect sensor....scan tool would easily prove.

 

[Vombrown]

Number 4 for a bad sensor. Take it in to any auto parts house and have them scan the computer for you. Should at least give you an idea. My first guess would be the CTS as mentioned above. TBI isn't a LOT better than a carb but at least it has the ability to sense the temperature and apply fuel accordingly. It shouldn't be so hard to start it and you shouldn't need to pump it up like a carb to get it going. I would look at the CTS first and then the fuel injectors.

 

[black dawg]

you will want to scan it at the engine temperature that it has trouble starting