Hard starting 1997 Tacoma V6?

Posting from IPad at 6 am so bare with me...

1997 Tacoma 3.4 motor. 350,000 miles.

I’ve been having hard start issues, not a starter or battery problem. The truck started gradually taking a bit longer to start last summer. Then the ecm fuel blew. Replaced the fuse and had no further issues with the fuse. A few days later the fuel pump went out. I replaced the pump but that did not change slow to start issue. The starting problem got a little worse so I replaced the pressure regulator (rear of motor behind the plenum). That did seem to help the problem a bit and it was a Toyota part, not a Chinese knock off. That didn’t really help much, still slow to start. So a couple days ago it got very hard to start. Now I can’t be sure of this but it may seem to start a little better after setting all night than it does after setting a couple hours. But the crank time is 15 to 20 seconds of trial and error cranking before it starts and when it does it sputters to life. After it starts it runs great. I’m looking at maybe something up with the relay under the dash. I had it out when I diagnosed the fuel pump issue. I also recently replaced the timing belt between the time of replacing the ecm fuse and replacing the fuel pump.

Any ideas?

Edit.....

Found the area of the problem. As listed on page 2 of this Forum topic, I pulled the open circuit relay which is under the dash above the fuse panel. I had tested it earlier when I diagnosed the fuel pump. It tests good. I pulled it and tested it again as listed on page two of this topic. Still tests good. BUT, now the truck starts perfectly. There are two things I'm suspicious of, One is the relay. Intermittent problem maybe. Two is the clutch bypass circuit. I'm still watching that, the problem I thought I saw might be nothing. But as it stands right now, the truck starts just fine cold or warm.

Edit, Update.. 1/10/2021

I took the truck to the airfield where I goof around and there is a Toyota shop foreman there who I told talked to about the problem. He asked about all the information that is in this thread. He asked to hear it start so we went and started it. He instantly said ignition switch. I'll have to order that. I'll be in New Mexico this week and will do the fuel pressure testing while I wait for the switch. Ignition switch makes since to me because it often starts after I release the key and that's exactly what it did when I released the key. But this guy has been a Toyota mechanic all his life so I'm sure he knows his stuff. I have been suspicious of the switch but that things is 400 bucks through Toyota. Ill try the Toyota salvage yard in Denver on the way down to New Mexico before I order it.

 

Did you replace your fuel filter when you did your pump?

also when was the last time you did spark plug?

 

Its a fuel injected truck meaning the engine is controlled by a computer
Before throwing more parts and cash at the truck , have you considered scanning for codes ?

 

Plugs and wires are new. Fuel filter has about 20k on it.

 

No codes, checked that.

 

Have you measured fuel pressure ?

 

Pressure tester is setting in New Mexico with the rest of my tools. Borrowed one from parts store rental and it was junk. Wouldn’t work.

 

I wonder do we have leaky injectors fouling plugs then needs to crank long enough to clean plugs??

 

I

Injectors are new. Had an issue about 90k back with one that wouldn’t fire so I replaced them all with new Toyota.

 

its worth having a Factory service manual (FSM) and you can follow the troubleshooting for your issue.

But look at the matrix I posted, if engine cranks normally whether hot or cold but doesn’t turn over then the process is 1-starter signal circuit, 2-fuel pump control circuit, 3-compression.

If the issues is when it’s cold engine then 1-SSC, 2- fuel pump control circuit

If the issue is with a hot engine then 1- SSC, 2- fuel PRESSURE control circuit, 3- fuel PUMP control circuit.

it’s worth having a FSM so you can follow each process so you dont throw parts at your truck. Been there done that.

 

Timing belt replaced check to see if its on its marks ?
igniter connection
ECM ground --- all grounds ?

 

FREE FSM !!!!!!!!

http://web.archive.org/web/20110102225436/http://www.ncttora.com/FSM/

 

It’s worth noting that I have the 96 FSM, but it should be the same for the 97 as far as in aware

 

Timing belt is dead on, I’ve been checking grounds all around and haven’t found anything.

 

Yea, I don’t have the FSM. Just a chitons and Haynes manual. The compression is perfect for the miles. I’m really leaning towards the fuel pump control circuit. Two relays on in the box and one under the dash. The relays for the fuel pump and heater{I think) in the fuse box are identical. I switched them around and it didn’t change anything. That leaves the one under the dash. I should be able to bypass it and see if it will start.

 

she could just be worn out... check compression on all cylinders before trying new parts.

 

Nope, great condition. I’m expecting another 400k easy. It’s a Toyota, not a Chevy.

 

FREE FRACTORY SERVICE MANUAL !!!!!!!!!!!!

HIT THE LINK @tim81499


http://web.archive.org/web/20110102225436/http://www.ncttora.com/FSM/

 

Do a Compression test and a Leak down test ---------- they are different and will give you the health of your motor.