Joust

My truck seems to crank more to start than it used to.
the colder it gets the more it needs to crank.

here is the kicker.
The cold start injector is working. I know this because I measured the resistances on the timer and ...
I spliced wires into the cold start injector plug. I run them to a small PCB in the cab. i put an LED to ground though a resistor on both wires.
This way I can monitor the lines.
When the truck is cold. Only one light comes on and after a good 5 seconds of cranking the other one comes on too. (This means they are both at 12v and the injector is off. i.e. no voltage drop across the two) It continues to crank till it starts.
I put a switch to ground on the line that turns on second. this way I can short it to ground completing the circuit to turn on the cold start injector.
If my battery can last long enough, I can always get the truck started.
When it is below -25 that is tough and need a second battery or a boost.

Whats the real problem?
could I have a weak fuel pump?
looking for opinions.

Steve777

So does it start faster when you use that switch which leaves the CSI on for more time? When you're cranking and it doesn't start, is there a gas smell at the exhaust?

I'm guessing that the switch to turn the CSI on longer did not help, and there is no gas smell. If that's the case, it would point to the CSI not really injecting gas when it's supposed to.

Have you measured the resistance at the CSI terminals? Have you tried putting 12v and ground to the CSI terminals for a sec to see if there is a click indicating that it is opening. Might also want to take the CSI out of the plenum and see if it sprays gas for a few secs when you are cranking (careful on this, have a jar or something to catch the gas right at the CSI and no smoking, sparks, etc, etc)

Joust

Yes I measured the CSI and tested it with jumpers to an external voltage source. I even removed it to see if it was squirting fuel. it is. it is not the CSI itself.

this is why I'm leaning towards fuel pump being weak. I'm at a loss.
I suppose I should rig in a fuel pressure gauge somehow.

sam333

Interesting what you did with the CSI wiring. Those low temps will test any system,( where do you live)? I would check your pressure like you said, also add some gas treatment for possible water in your fuel. You could have dirty or partialy clogged injectors( bad atomization).

Joust

I live in the Ottawa Valley in Ontario Canada. It was -31 degrees last sunday. That's about -28degF
the gas we get here is 10% methanol so that's a lot of built in gas line antifreeze. I doubt that's the issue. and I always fill the tank completely to avoid excess condensation build up.

wyoming9

iTrader: (1)

When was the last time you did a major tune up ??

Changed the fuel filter lately??

What weight oil are you running??

Condition of charging and starting systems ??

Condition of battery terminals cables etc??

How does it start once it is warmed up after driving 10 to 20 miles??

Once all the gear oil in the drive train is warm how does it drive??

In the cold all these things play a roll in getting started in the cold. If the wind is blowing it just compounds the problems.

Have you thought of a block heater!!

In eastern Pa it doesn`t get cold anymore (global warming) so I don`t have the cold weather starting problems. Only one day has been below 0 F:jessica:

Joust

When was the last time you did a major tune up ??
i replaced teh head gasket in the fall. at the time I replaced teh plugs and filters. I did not do the fuel filter.

Changed the fuel filter lately??
but if it was the fuel filter, I'd expect more consistent problems and not only when its cold.

What weight oil are you running??
5w30 synthetic.

Condition of charging and starting systems ??
14.25volts

Condition of battery terminals cables etc??
battery is a 1000cranking amps new last spring.

How does it start once it is warmed up after driving 10 to 20 miles??
it starts very well. it still has to turn over 5 or 6 times which is more than normal IMHO.

Once all the gear oil in the drive train is warm how does it drive??
it drives fine even in the cold before it gets a chance to warm up significantly.

In the cold all these things play a roll in getting started in the cold. If the wind is blowing it just compounds the problems.
agreed

Have you thought of a block heater!!
i'm in the process of finding one.

Joust

interesting development.
when I turn on the key, I don't hear the fuel pump.
went searching. turns out this is normal.
http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump
the fuel pump is enabled by a switch in the Flapper AFM. so I jumpered Fc to B+ and i could hear the pump.
tried starting the truck with this jumper on and it fired up within 3 cranks.....Hmmm
this morning it was -23deg.
went out, put on the jumper and the truck fired up within 3 cranks. Awesome.
got immediately out and pulled the jumper and the truck sputtered and died in 3 seconds.
I definately have a relay issue.

Steve777

Need to check the wiring diagrams to be sure, but IIRC Fc to B+ just bypasses the flapper switch in the AFM. So if putting that jumper in makes it works (as it seems to here), it would mean that the switch in the AFM is not doing its thing (or connector or the wiring to the AFM), but that the rest of the fuel system is OK (relays, wiring, FP etc).

Joust

I jumpered Fp to B+. not Fc. i basically turned on my fuel pump all the time. as long as my key is on.
But I agree it is could be the flapper switch.
I'll check this as soon as I get home tonight. and try to jumper Fc to ground.
gonna have to build another test jig with two switches on it. at least this one can all be done inside the cab.

the Flapper switch is not used at engine start.
it is used once the engine has started and it used to maintain fuel pressure while running.
see this
www.autoshop101.com/forms/h42.pdf page 8
since my truck stops when i pulled the jumper and it was cold. that leads me to believe it is the flapper "Fuel Pump Switch"
but that still does not explain why it doesn't start.
I think it is the relay because it is common to both starting and running.
It'll be easy to determine once I can get in to it with a meter.

Steve777

Opps, typo, meant Fp to B+.

Here is a test procedure for the AFM and that switch:

http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

It's the E1-FC tests...

Could also be the connector coming loose too. Or just enough of an air leak after the AFM so that the flap is not pulled open anymore, turning off the pump...

89pickumup

have you turned key on and listened for a prime
dunno if there the same but i had a jeep and was hard to start like that long story short the fuel pump wasent kicking in untill the check engine light came on in dash and so it wasent priming so it would just crank and crank then light come on and vroom ended up being a wet computer in my case but im just curious if mabye yours isnt priming either
mine got worse with time id leave key on for up to 5 minutes before it would prime before i finally pulled cover off my computer and saw where the water had gotten to it
so mabye try just turning key awhile dont crank and see if after a min or so you hear the pump kick in
o yeah and probly should have mentioned that the problem was worse the colder it got lol

Joust

OH Yeah!!! I think I found the culprit.
I removed the Relay when I got home and it was covered with some sticky gunk.
I popped the black top off exposing the innards and the Capacitor inside leaked all over. it is an electrolytic cap that in series with the resistor makes a charge circuit to hold the relay on if the flapper closes for a second while the engine is running. if that cap cannot hold a charge, it cannot turn on the relay.
i took some pictures that I'll post after I'm 100% sure I solved the problem.
I soldered wires onto this relays 5 lugs and run them to a breadboard so that I can measure the voltages on my passenger seat before during and after starting.
but even at -17 plus a good cold wind the truck started right up without the aid of jumpers. I'm optimistic that was the smoking gun.

on a side note. that Cap is easy for anyone to change. The change can be done with a small screw driver. not even any soldering required.
Its a 15¢ part and Toyota is charging $175 for its effective replacement. Can you imagine?
I didn't have the exact part (130uf @25V ) so I made up an equivalent using a 100uf in parallel with a 47uf both @35V. the little extra will give me just a tad more pump time on after the engine dies.

Northern Sun

First of all , i would like to say hello to Yotatech and everybody here, ill post some info here, im new here but old elsewhere

Im more than sure i got similar problem to urs, for last 4 yrs i used manual choke instead of automatic cold start momentary fuel injection, simply saying i used manual adapter with adjustable voltage to adjust amount of fuel so i can start my 3.0 v6 90 during cold weather; it did the trick, but i decided to give it a try once again
in my case is a combination of fuel(fixed)system. Ignition, distributor(3coils pass), Vaf is from other truck, (8.56X4 - oppose to other one i had b4 4.69 or 3ohmsX4) throttle pass, all waterjacket sensors pass, o.e.m harness life span

but i did had working csi b4 b4 i changed hg lol

and my conclusion so far as of ysterday is that im simply not getting juice accross to/from ecu/ecm; i also had notice for longer time now that durning test bulb proccedure, my engine light comes 'ON' always last, weird no ...
i doubt that, vacuum/intake system is actually pretty good, kept in good condition offcorse

Joust

Thanks 89, I thought of that. but these trucks do not turn on the pump when the key is on.
look at the linked pdf I put a couple posts up.
There are two separate coils on the fuel pump relay (circuit opening relay)
One turns on the pump when the ignition switch is in the START position. so you can only get prime while cranking.
the other is activated by the Flapper AFM being open. i.e. engine is running and sucking significant air for enough time to charge the RC combination inside the relay housing.

Joust

here are some pictures of the problem.
the green cap leaked its electrolyte.

Joust

Here is my fix.
I didn't have the same cap. but the addition of two caps makes a close enough equivalent.

I soldered some cat5 wires onto the relay so I could take some measurements.
today it worked like a charm. Started on 3rd crank but it was only -16deg.
this weekend is supposed to be cold. We shall see.
Worst case is, I'll mount a switch in the dash from Fc to ground and use that to prime my pump before starting. I'm optimistic that I won't have to.

Northern Sun

interesting, this is one thing i didnt touch yet, how did u know it leaked? visual inspection? what is the size of these caps u have used?, ill definitely have mine apart and see, what the hell is happening inside.
Let me ask u a question, how is ur ignition coil? every coil i can find brand new or used, basically doesnt pass primary, weird .., does it even makes that much difference?, im guessing it wouldnt really matter if i had a ignition coil like that to fix my cold injector harness cable having power. Anything above 4v is good

Joust

See post #13.
and the pictures show the leakage all over the place including the brown stains on the plastic housing.

Northern Sun

alright, thanks