jjmoss99

This spring I swapped out my 1991 3.0 with a 3.4 out of a 2002 4 runner. I love the power and it runs good. The issue that I have is focused to when starting the motor. There are two issues (I think)

1. The motor hiccup's sometimes when turning over. It sounds like a the voltage drops while cranking and the speed of the starter slows down then picks up. Sometimes the hiccup is severe enough it sounds as if the starter solenoid is engaging and disengaging while attempting to start. It can sound really bad. It will happen when the motor has sat all night as well as after i've driven it for a while and warmed it up.
2. The starter sometimes doesn't turn over when the key is turned to the start position. The starter solenoid will click but won't start.

Items i've changed include:
New battery - Helped make the starter spin faster but hiccup still remained.
New Starter - Sounded a little better but both issues remained
New 2 gauge cable between Battery and Starter - Significantly reduced the severity of the hiccup and delayed start.
Added a second ground from battery to motor

By changing these out the issue has decreased but still seems to occur occasionally. I haven't been left stranded but I'm fearful that it will. I was thinking the times that it doesn't start and just clicks was heat soak on the starter because it only seems to do it when it's hot. The last two times it's happened was after I pulled my expedition trailer up a steep grade on a hot day and then killed it backing into my camping spot. Today it did it in the parking lot after my pickup had sat for 10 hours but it was near 100 degrees out.

I have a 600 mile backroads trip planned for this weekend and i'm now looking at hooking up my expedition trailer to my GMC so that I don't have issues and are paranoid every time I shut off the motor. Any help is greatly appreciated. Thanks.

Justin

gryphonrunner

Have you checked your starter trigger? it's possible you have a short or, more likely, an open circuit somewhere in the path. That would cause the solenoid to turn off and on. If it's only partially turning the solenoid on, it will reduce the amount of current flowing to the starter motor (resistance is inversely proportional to the holding strength of the solenoid coil) which will cause the starter to slow and/or hiccup. Along the same lines, you could have an issue in your ignition switch. If you can easily get to the starter trigger wire, I would disconnect it and watch the voltage on it while someone turns the key. That's my best guess based on my knowledge, but the starter circuit is pretty simple so there's really only so many things it could be and you've already tried most of them. Good luck!

Patrick

jjmoss99

Ok thanks for the help. I was thinking about running a wire from the battery to a fuse then to a momentary switch in the cab, back out to the starter and this would bypass the starting circuit to see if the issue happens. Then I figured I could turn the key to the on position hit the momentary button and start the motor. Or do you think i'd have to turn the key to the start position then push the button. This is obviously only a short term test to see if the issue goes away. Thanks.

Justin

gryphonrunner

The problem is the fuel pump only runs when A) the motor is running as determined by the ECU or B) when the key is turned to the start position. As a result, you may occasionally not have enough fuel pressure to start the engine unless you either turn the key to start long enough to prime the fuel rails or you rig up a fuel pump override. An override shouldn't be too difficult if you have the EWD if you do want to try that.
Another thought did occur to me this evening. Is it possible that the starter gear is binding on the flywheel due to a misaligned starter? It's kind of a long shot, but if the starter can't freely turn the flywheel, it mind bind up and act like it's not getting good power. The issue could be worse when the flywheel is hot and therefore slightly wider in diameter. My money is still on the solenoid/starter circuit, but if that checks out, I would look at the starter and see if you can rotate it away from the engine by just a few millimeters. If it is binding, that may be enough to free it up.

Patrick

jjmoss99

Awesome. I think i'll give the wire and momentary switch a shot and see what happens. If that doesn't work i'll take a look at the starter and see if it could be binding. Thanks again for your help. When I find out more i'll report back.

Justin

jjmoss99

About a month and a half ago I built the wire and momentary switch in the cab and bypassed all ECU starter circuitry, clutch switch, etc to the ECU. I've been starting the pickup manually this way ever since. The symptoms have seemed to decrease somewhat. Now, when I start the motor when it's cold, the motor starts fine, no issues. After it's warmed up and I shut it off, every 2nd or 3rd time I go to restart the motor the starter will pull down. It almost seems like it could be a timing issue.

I think my next step is to wire in an OBDII port and see if there is a code that will lead me in the right direction.

Any thoughts? Thanks.

Justin

gryphonrunner

I had to do the same thing. I bought a cheap OBD2 plug and Bluetooth adapter off EBay and wired it into the ECU. I would definitely recommend going this route because these are a pain to diagnose without them.

jjmoss99

Does anyone happen to have the Service Manual for a 2002 4 Runner? I still haven't been able to find the wiring schematics for the OBDii port. I just want to wire in a port to the ECM so that I can pull the codes and try and resolve this issue. Any help would be appreciated. Thanks everyone.

Justin

Thommo Thompson

Are you sure youve replaced the battery with a capable CCA battery? the 3.4 is bigger than the 3 so perhaps the battery needs to be upgraded?
I know that Cold Cranking Amp issues are made particularly worse by resistance in wiring, so the changing of all the parts that gradually made it slightly better would line up with an "under spec" battery.

jjmoss99

Yes, I spec'd out a battery at NAPA for a 2002 4 runner. The motor will turn over and start fine when it's cold, even down into the 20's with no issues. But if I warm it up to operating temperature and then shut off the motor, it seems as if there is a timing issue or a cylinder firing at the incorrect time because it will pull the starter down as it attempts to turn the motor. I'm hoping that I can find a code to lead me in the direction of what may be wrong. Thanks.

Justin

Thommo Thompson

hmm, is this still happening at all?

jjmoss99

No. About 4 months ago I ran a wire from the battery to a momentary switch that goes directly to the starter and bypasses all the starter circuitry and it hasn't done that since. I believe that I have two separate issues going on. The noise it makes when the starter slows down doesn't just sound like a low voltage issue with a battery, it sounds very unhealthy like something in the engine is resisting being turned over. That's what makes me think that it may be something with the timing especially when it only happens when I try and start the engine while it is at operating temperature. I'm assuming that the ECM could be attempting to change the ignition timing but a failing sensor (or something else) is causing an issue. Thanks.

Justin

Thommo Thompson

ok well, take note of this..
Hot starter motors, (hot from sitting next to running engine) can short out on the armature when they get hot due to warping of sometime inside them.
I have personally seen this and verified it as the problem on 3 separate occasions.
In a 1980s toyota 4K,
a 1990s Suzuki f6A and
a 1990 Ford econovan motor, i think it was a 2.0 FE.
After you replaced the starter (if it was indeed with a brand new unit) are you still getting this kickback effect?

jjmoss99

The kickback that is happening with the motor happened with the starter that came with the engine. I figured that it could be an issue with starter so I went to NAPA and purchased a new starter (or reman'ed) and installed it. The kickback issue was still occurring after the new starter was installed. I've replaced just about everything that has to do with starting the motor. I've even ran new #2 cable from the battery to the starter and added a second ground from the battery to the block. Thanks.

Justin

Thommo Thompson

bugger.
does kinda sound like a bombuation even buy i dont think we can move onto that yet.
electrons flow more easily through metals when they are hotter, so sometimes, if there is a short somrwhere, that short can be made worse when temps (ambient or engine bay) are hotter. as someone else mentioned, this can be a short anywhere along the line that supplies power to the starter solenoid.
where exactly did u route the bypass starter switch that u made.
did it go directly from battery to switch to solenoid? if so then it could still be one of the other original circuits shorting to earth while the motor is crankin and shaking.

jjmoss99

Yes the wire was ran from the battery through the firewall into the cab to a momentary switch then back out the firewall directly to the solenoid on the starter. I'll start looking at the wiring and see if I can find anything that may be shorted out.

Justin