When it's cold it takes 3 to 4 tries before it starts.

Took a couple of tries to start this morning, fired up then died a few minutes later. Then died on me driving to work, coasted to the side of the road. Started right up and drove off. No codes. Gonna tap into the fuel pump wire and monitor it a little closer.

 

Ok I am set up to test the fuel pump voltage on the fuel pump side of my soldered splice for the morning cold start.

I did start it hooked up and I had 13.5 volts for a few seconds then 8.5 volts after it was running.

 

Would not start this morning. Meter was reading 13v fired up then dropped to 5v and died. After about 8 tries. I swapped out both relays and it fired right up with 14v start and 9v idling. Got down the road about a half mile and it died. Fired right back up and drove to work (10 miles).

No further testing.

By the way I live in Kuna Idaho and it really isn't cold at all.

 

Definitely losing power to the fuel pump. Took three tries to start again then died on the way to work no codes voltage drops to 5v and dies.

Any more advice on where to check next would be greatly appreciated.

 

If all else fails, run a compression test. Some models had low tension rings, and need to be replaced. Can't say about Tacoma's but on Toyota cars it shows up.

 

Connected a broken wire for the hood switch from the remote start. Cleaned a couple of plugs with contact cleaner. Replaced 3 clamps on vacuum lines cleaned and sprayed contact cleaner in relay sockets. Battery was disconnected during this whole process. Need a diagram for the fuel pump electrical system so I can track down all the ground locations to inspect and clean them. It took 10 tries to start up this morning and stalled on me on the way to work took ten more tries to get it started then drove it to work. This will be my last ditch effort to fix this myself. Any more ideas will be appreciated.

Next I will check the yellow and red wire going to the ECM. Should have 12 volts going in from fuel pump relay, correct?

 

Here's the wiring diagram, I won't be able to help much till later tonight.

 

Cleaned a few grounds under the hood, checked the ground and hot wire on the plug at the pump. Redid my soldered splice with a but connector was getting funny resistance readings on my meter. We will see what happens in the morning. I did set up the voltage meter again to watch in the morning for start up.

 

After everything I did yesterday no change in the morning. I did hot rod it a little bit and at least it stayed running for me on the way to work. IDK I'm out of ideas.
The best results I had was cleaning the throttle body It fired up every day for a week. Maybe it has something to do with that?

 

Are you losing power to the fuel pump just before it stalls?

 

Skimming through the thread it looks like you checked some grounds.
Is the starter and remote start grounded well.
Your description of the starting behavior is how mine acted after dunking the starter in some creeks.
Moisture in the morning, turns to vapor when it's warmed up but condenses back to liquid when cool.
Giving those rough morning starts.
Bad ground, dirty contacts?

Food for thought.

 

yes, drops down to around 4-5 volts then dies.

 

That kind of suggests something is heating up and losing connection, unless something else aftermarket is tapped into that circuit you have the EFI fuse, EFI relay, COPN relay, Fuel Pump relay, Fuel Pump Resistor, and a junction.

I think mabe bypass the Fuel Pump Resistor temporarily and see what happens.

 

Ok, in the morning I will bypass the resister and see what happens. Can I drive it for 20 minutes jumped like that?
Should I check the resistance on the resister when it's cold or warm?

 

I don't see why not, it's just running the fuel pump faster. Pressure is still regulated by the fuel pressure regulator.

Probably should check it when the problem is happening.

 

I drew a line on the circuit we're worried about being we have a voltage drop not a complete loss of voltage. The problem would have to be somewhere in that circuit.

 

I agree with you. Bypassing the resistor did not change anything. Engine died first two attempts started 3rd try. Died a quarter mile from the house after 5 tries it started and ran fine.

 

This was Idling after I hooked the resistor back up and it through a P0102 code today coming home from work so I bought and installed a MAF sensor. The sensor reading before I changed it was at .5 not much change...

 

I wouldn't toss the old sensor yet, I bet it's not your issue.

I'm kind of suspecting the EFI relay at this point, maybe check voltage drop between battery positive and the EFI No 2 Fuse (10A) with the truck running.