Engine starts and shuts down

Hi folks...new here and am very perplexed. I have an 08 dbl cab. VVT-i V6. I have never had trouble with this truck other than the rear breaks...that ended with a screwdriver stabbed thru the fender. Anyway heres the problem..

From time to time...about once per day.. I can start my truck and it will run for 2 seconds than shut down. I restart and it will do the same thing. After 3 to five attempts to start the engine will fire for just a moment (more of a cough)....than nothing. If you contenu to hold the ignition swith.. The engine turns over and wont fire at all untill I turn the switch completly off and tray again.

This battle can last for 5 min to an hour...than it will start up like nothing ever happened.

At first the event would happen once a week now its every day. Usually it happens when the engine is warm.

I cleaned the MAF/IAT sensor but no change. I had it scanned for coded a while back and there were none...no check engine light...nothing.

Today when it happened I disconnected the MAF and tried to start it to see what would happen....it did the same thing. I scanned again afterward and a code popped up. P0102 MAF circuit low input voltage....that is probably tripped because of me trying to start the engine with it disconnected.

I also removed one coil from a spark plug...inserted a spare plug and looked at the spark.....it looked weak and actually got weaker untill it didnt spark at all. This was done while my wife turned the engine over for about 20 seconds. Could it be a bad set of coils....ignitor?

Im starting to think its been parked too close to my wifes crysler too long.

Suggestions....starting point....prayers please!

 

personaly I would be looking at the fuel pump first. Do you have fuel pressure?

 

I havent ruled that out....for now I have no way to check the pressure...can i make the gauge or do i need to buy it...i can see some odd connectors on the fuel lines and im not sure if i can simply cut the line and insert a T fitting.

 

The weak spark on turnover could be due to low voltage after trying to start it for so long. It shouldn't be a spark issue, because you said it runs for 1-2 seconds at first. That means you're getting spark, so its probably not getting fuel.

My first inclination on something like this would be to check the fuel pump. The truck is old enough now that it wouldn't be surprising to see it go. Check for fuel pressure, I'm willing to bet that's the issue. It sounds like its beginning to fail intermittently and will go completely soon.

you have my curiosity...

 

Best way to check the pressure? I will say that aftet having the truck parked for 1 hr...there was no pressure stored in the fuel lines. I dont know how long it would hold pressure. In the past when I disconnected the lines on other cars I would get a good spray even if the car sat all day without running.

 

http://www.customtacos.com/tech.old...6toyrm/06toypdf/06rmsrc/rm2006ta/00501110.pdf


http://www.customtacos.com/tech.old...6toyrm/06toypdf/06rmsrc/rm2006ta/00500910.pdf

http://www.customtacos.com/tech.old.../06toyrm/06toypdf/06rmsrc/rm2006ta/009000.pdf

http://www.customtacos.com/tech.old...f/06toyrm/06toypdf/06rmsrc/rm2006ta/00900.pdf

Hope that helps

 

Not sure on these trucks, but my old firebird had a pressure test valve. Was basically a schrader valve that I could hit with a screwdriver. If it sprayed fuel, I had pressure lol.

 

If it turns out not to be the pump maybe you have a dirty or clogged fuel filter? They're really cheap and easy to replace, at least they are on the first gen 3.4l trucks

 

These trucks don't have replicable fuel filters, tank needs to be dropped and sock filter removed.

 

Thanks guys. I Have a buddy at work he has a test kit....were gonna check it tomorrow at work....and when it acts up too. I did change out the sparkplugs and that made a huge improvment. The electrodes were worn and the lil hook that catches the arch was worn thin...a cpl were almost gone. So.....im thinkin I need to check for more neglect....tranny fluid and the diff fluids....timin belt too. yey....more work...more money. I will post what I find out on the fuel system.

 

Well....the test kit didnt fit my fuel lines....i went to rent one from orileys...that one dont fit either.....it seems im getting screwed no matter what direction I go.

 

My competence on fuel systems is like a 1 out of 10. What if you turn the key on for 30 seconds, let the fuel lines get pressure, then start it up?

 

And just so you know, there is no timing belt. It has a chain and should last a lifetime.

 

Sounds like the beginning of a fuel pump to me. Bring it to repair shop unless you have a good chiropractor on standby. To verify without test kit have someone stand by filler neck and you turn the key don't start it the truck, pump should buzz. If it does then start and listen pumpshould still buzz while on for a while if it doesn't buzz its your culprit.

 

i have listened for the buzz....or hum from the pump....since i bought it in 09.....never herd it. Bout the best guess I can make for now is Tell the wife she aint goin shoppin....so I can get a new pump. If that dont fix it....i atleast know to look elswhere....it is due for a new pump and its atleast one thi g I know wont break for a while.

 

Did you check the pump relay as linked above. Hate to see you put in a pump for a 30 dollar relay that would take you 25 seconds to replace.

 

well if you want to check relay real fast fonfind the relay, and swap it out with another relay from the truck that looks the same and has the correct number of terminals in the same position as the fuel pump relay does. Plug it in and start the car and see what happens if the same symptoms occur it's not the relay if the car runs you solve your problems.

 

I did check...Drivesector...here is what I found.

On the FP relay...

Pwr off was 0 ohms on terminals 3 and 4. than 0.L on 3 and 5

Pwr On I got... O.L between 3 and 4. than 0.0 between 3 and 5


EFI relay was...

pwr off. 0.L.

pwr on.... .7 ohms

By the standard.....both relays are bad. My ohms meter is questionable so I will test it with one at work in the morning
Right now the engine runs fine even with the relays testing out as they did.

Human error?....Bad meter...to be contenued...

 

Before you spend a dime on anything swap a bad relay for a good one and see what happens.

 

roger that