**Solved***Long Cranks but runs when started

[brillo_76]

I sprayed starter fluid in the intake and it would run and then die when I stopped spraying.

Here it is.... Not getting fuel... If it fires and dies are starting fluid dead giveaway ignition all good... Proves that by firing...

Has to be injectors or fuel pump fuel regulator... The cylinders are not getting the fuel they need. Possibly Cam senor....

If its cam sensor it never should fire even with fluid... However, I had one cam sensor unplugged one time and the 5vz-fe still fired....

The cam sensor is easy to test. Plug reader in your OBD2 port.. Watch the rpms.. When your cranking you get RPM numbers, your Cam sensor is working.. Would be a few hounded RPM...

No RPM registering, your fuel pump not firing. Its why we have almost 3 second cold starts.

I don't recall the exact number when cranking rpm is though its almost impossible to see on our gauges maybe 200s??

 

[brillo_76]

Update- I think my issue is the cam sensor. Looking at the oscilloscope it seems like the signal is intermittent. Just keeping this thread updated for people following even though its not getting much interest lol.

Here is some footage of it.

- YouTube

Ive got a replacement on the way and will update after its installed.

Doing it this way, what does your buddies Crank sensor signal look like?? The same or majorly different??

That would prove it is that cam sensor or not..

 

[calimobber]

Yeah im going to install a fuel rail pressure test port this week just to know where it is but I know the injectors are not firing. I used a volt meter on the injector plug and it shows 0v when its acting up it cranks and stays at 0v so no signal and at the same time as it fires up the volts jump to 1v. Its prob alot higher but its happening so fast the meter only shows 1v instead of 12v. my noid test light arrives tomorrow so ill verify with those.

My theory is the crank sensor tells the computer enough for spark and as you mentioned and ive seen online the engine will run without the cam sensor because it defaults to a generic timing off the cranks info.

Since the cam is working ish its trying to use the cam/crank and its confusing the computer when its not lining up so it doesnt know when to fire the injectors until sometimes it lines up and starts working normal and it runs.

This is just my theory and ill know when i swap it but using my buddies is a good idea. I have read the signal when its starts fine and the signal did look alot more regular and didnt jump around. Im going to verify the timing and belt and all that when I swap the cam sensor and ill update everyone. thanks for the input.

 

[brillo_76]

Yeah im going to install a fuel rail pressure test port this week just to know where it is but I know the injectors are not firing. I used a volt meter on the injector plug and it shows 0v when its acting up it cranks and stays at 0v so no signal and at the same time as it fires up the volts jump to 1v. Its prob alot higher but its happening so fast the meter only shows 1v instead of 12v. my noid test light arrives tomorrow so ill verify with those.

My theory is the crank sensor tells the computer enough for spark and as you mentioned and ive seen online the engine will run without the cam sensor because it defaults to a generic timing off the cranks info.

Since the cam is working ish its trying to use the cam/crank and its confusing the computer when its not lining up so it doesnt know when to fire the injectors until sometimes it lines up and starts working normal and it runs.

This is just my theory and ill know when i swap it but using my buddies is a good idea. I have read the signal when its starts fine and the signal did look alot more regular and didnt jump around. Im going to verify the timing and belt and all that when I swap the cam sensor and ill update everyone. thanks for the input.

Intermittent cam sensor signal could very well be causing this... Would explain how it runs then then wont start....

The injectors I thought would be a signal not just dc..More of a waveform of on and off ... Should look more like a digital wave.. I suspect the your on the right track.

These are old enough to have sensors issues.

 

[FD7683]

I don't have any advice but I wish you the best luck on this problem I had mine go out completely without a real warning it just stumbled and died. What I can tell you though is these Toyota trucks usually take a lot of cranks to fire up but I'm definitely sure you know about this. You should be investigating the fuel pressure regulator real good it definitely sounds like its the issue since it sounds like it doesn't hold pressure and takes long to crank.

 

[calimobber]

Welp ....didnt fix it.

Replaced the cam sensor with a NTK from genuine seller. Installed my fuel pressure test port and its holding 45psi. It fired up and I let it idle a bit to warm up then turned it off. It held the pressure fine for a few min then started again and it cranked forever. put the noid light on and its what the volt meter told me. Not firing injectors until the car starts.

Going to pull my buddies crank sensor this weekend. Im at a total loss man.......

 

[calimobber]

The injectors I thought would be a signal not just dc..More of a waveform of on and off ... Should look more like a digital wave.. I suspect the your on the right track.

These are old enough to have sensors issues.

Yeah thats the injector signal, I havent bothered to check that. I think thts more for running rough or something. i can put the osilloscope on there for fun once its running, but once it fire up it have no issues. I the service manual have the proper wave forum for it.

Its just seems like the ecu is waiting for something to send the signal, just dont know what the issue is since I have no lights.

 

[brillo_76]

Yeah thats the injector signal, I havent bothered to check that. I think thts more for running rough or something. i can put the osilloscope on there for fun once its running, but once it fire up it have no issues. I the service manual have the proper wave forum for it.

Its just seems like the ecu is waiting for something to send the signal, just don't know what the issue is since I have no lights.

As far as i know, that would be camshaft position sensor... As the EFI needs to know the position of the camshafts. Then after it sees that signal it fires the fuel pump. Safety feature so fuel wont spew in case of crash if the engine can not turn.

I am thinking you see this when you put a fuel pressure gauge in the fuel line.
no pressure from your issue with camshaft sensor.

These rigs are too old for advanced diagnostics so it wont say hey the camshaft sensor messed up. Or something else missing...:-(

 

[calimobber]

Welp.... Swapped my buddies Crank sensor and same issue. It started just fine so I let it idle for a few mine. turned off and turned back one started fine. did it again and it cranked forever lol. held it for a good 10 seconds just to see.

I put a charger on it just to see if the higher voltage or starter cranking speed mattered. Its cranked way faster but nope...same same.

 

[brillo_76]

I am running out of ideas...

 

[calimobber]

I am running out of ideas...

You and me both buddy haha

Im just lost at the moment. Going to have my buddy come up and work through every step again so I can crank and he can check to be sure the volts at the injector stays on while cranking( its there when the key is on) cause idk what else to check

 

[brillo_76]

You and me both buddy haha

Im just lost at the moment. Going to have my buddy come up and work through every step again so I can crank and he can check to be sure the volts at the injector stays on while cranking( its there when the key is on) cause idk what else to check

May do nothing but swap the back of your ignition connector with your buddies.. See if it that does anything. Maybe it will fix it but a quick thing to role out.

 

[calimobber]

So I might have fixed it but i will start with this, There is another thing the ecu is looking for, im surprised no one else mentioned this. Talking with AI i learned the ignition box has a wire called the IGF wire. This wire apparently sends a signal to the ECU telling it the spark plugs have started sparking its okay to pulse the injectors.

I guess its a safety thing so it doesnt keep spraying fuel into the cylinders and not burning it. So i checked for that signal and it was there. Its a 5v pulse you can pin the wire and ground it with a oscilloscope. I did swap my buddies ignition and it didnt change anything.

.....So onto the maybe fix. so ive been testing everything from the back of the ecu connectors so im seeing the signals on the wire from the sensor not whats the computer is seeing. I started thinking more and more and decided to use a little pick to try to force the connector pins closed for the crank sensor to make a tighter connection for the ecu pin. After doing that the trucks bee starting normal all day. Im still not convinced and dont trust it since i feel like ive been here before but maye all this time when i see the sigal from the crank sensor the computer itself is seeing a degraded signal and confusing the computer.

I did try to see the crank signal with ob2 scanners but it was jumpy and then looked normal when the car started so looked okay.

Ill update this after my camping trip next month but fingers crossed it was the ECU pins on the connector.

 

[calimobber]

So after all this it ended up being the scan gauge. IDK if its the cable or what but I found out because it would not start and I left the key in the on position. As I unplugged it to plug in a more advnaced scanner I noticed the check engine light came on. I tested it a few more times by plugging it in key to on no check engine crank crank. unplug the light came on and it fired right up.

So Id unplug it for testing and it would run fine, then Id go drive and plug the scan gauge back in. The gauge was reading just fine when driving so never knew there was an issue. I would still start somethings when plugged in so that made it harder to solve.

At this time im not sure if the cable is bad( ive had it for 20 years) or there is other issues and plugging it in shorts something but ill reach out to scangauge and order a new cable.

What I learned out of all this make sure the check engine lights on when you turn the key, if its not the ecu isnt on and there is a problem.

 

[brillo_76]

Glad you figured it out.