The starting system on my 4Runner (88 22RE) has been acting up. I replaced the starter today to rule it out. Here's where I am so far:

- When cold, truck will start easily.
- After it warms up or even after running for a few minutes, it will not restart. Starter will crank the engine over at a normal speed but the engine will not fire.
- If it is allowed to sit for 30 minutes or so it will start up fine again. If I turn it off and try again, it usually will not start and I have to wait again.

After some Googling and reading some great posts courtesy of 4Crawler, I am led to suspect the Circuit Opening Relay (COR or CO). Here are details about it from 4Crawler's site:
http://www.4crawler.com/4x4/CheapTri...ORelayLocation

I found the relay and removed it. Resistances all check out within spec. When voltage is applied, the correct terminals show continuity as per the FSM troubleshooting guide.

What I have NOT done is attempt to check the output voltage or operation of the relay while it is in the truck and trying to start it in the engine-hot condition.

Jumping the Fp / B+ terminals in the passenger side underhood box does indeed cause the fuel pump to run when ignition is on, but it does not allow the truck to start.

I ordered a used COR from eBay (same part #) and hopefully this will fix it.

Any ideas or guidance would be appreciated. Thanks.

 

Toyota put in a VSV (blue) to help with hot starts. When the motor is hot, it feeds manifold vacuum to the Fuel Pressure Regulator to up the pressure and prevent the fuel in the fuel rail from turning to vapor instead of a liquid.

I would run the vacuum hose that feeds the FPR that comes off of the VSV directly to the manifold vacuum port. There is enough line there to do it. Leave the electronic connection hooked up as it will not hurt anything. Your basically just bypassing the VSV. If this fixes your hot starts, then you know it's the VSV.

I have mine bypassed when I had the same issue, never had a hot start issue again...

 

Thanks for the idea. I think I bypassed mine a while ago, but I will check and make sure I hooked things up the right way.

 

Double check your VAFM as well. Check the terminal with a multimeter per the FSM. A malfunctioning VAFM (or IAT) could cut power to the fuel pump, rendering it useless until it cools down.

 

Good call on the VAFM check. This turned up some interesting stuff. I used Roger's troubleshooting guide: http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

The E2-VS circuit is the one that is supposed to gradually increase resistance as the vane opens further. Well, in this case it just bounces around. Sometimes when the vane shuts it reads out of spec (greater than 400 ohms).

The FC-E1 circuit is what turns on the fuel pump. On the bench it seems to work fine, though it feels like the vane has to move through about 5 degrees before it goes from infinity to zero ohms. I warmed the engine and then applied a meter across the FC-E1 terminals on the VAFM. A helped cranked the engine (did not start) and the resistance remained infinity. It tried to start once or twice and resistance dropped for those moments.

I found that I can jump the FC-E1 terminals on the VAFM connector (not the VAFM itself) and the fuel pump will run with the ignition on. Doing this sometimes the engine will begin to start roughly, and I can quickly plug the connector back into the VAFM.

Both of these findings lead me to believe that I should swap out my VAFM as part of this troubleshooting process.

 

Here's how I have the VSV line hooked up:


The line goes directly from the FPR to the upper plenum port. Is that what you meant? The connector for the VSV is not hooked up (VSV is gone). I tried jumping the connector and it did not affect the hot start -- just curious.

 

You should probably take a look at this TSB too.
http://www.toyotapart.com/22R-E,_22R...T-EG011-89.pdf

If you haven't already.

 

Thanks MudHippy, I had never heard of this! The affected models do not include 88 22RE... are they applicable anyway? The second page leads me to believe that these changes were applied in the 88 model year.

 

Yeah, I don't know if they would. They might not be. The last guy I showed that to here was in the exact same boat. 88 22R-E hard start issue after the engine got hot. And he was wondering the same thing about it(the TSB). I don't suppose it's out of the realm of possibilities that they screwed a few up at the factory. Like put the old part(s) on, instead of the new one(s).

Just throwing it on the table. I was actually thinking it might give you some other ideas as to what the problem might be. If nothing else. Wasn't sure if you'd thought about checking/replacing the CST switch or not.

 

Replaced the VAFM with a used unit, same part #. Did not fix the issue, though it runs a little better (I think the resistor strip was a little worn in mine).

Also verified that when the hot-start issue is occurring I do have good spark and fuel is being delivered through the rails. I saw this by loosening the cold start injector banjo bolt slightly. Cranking the engine resulted in a strong flow of gas.

The failure appears to be the ECU not telling the injectors the fire. Waiting on the new COR to rule out that suspect.

 

That's correct.

Also, I would also look to see if your fuel pump regulator is working properly and upping the pressure to prevent the fuel in the fuel rail from vaporizing.

 

How would I check this? Also, would you expect the FPR to act up all the time? Once running the truck works well with no issues...

 

I had a similar experience which led to just replacing parts, even though they verified "good." One turned out to be an ECM coolant switch that had gone way south with minimum temp changes. Also had a Air Flow Meter that gave me fits on another one But I finally caught it out of specs and after replacing it, fixed the problem. In both issues no CEL.

 

any codes

 

It might be your ECU (ECM) but it most cases unless you see some sort of blunt damage or water leaks, it's not likely.

I totally forgot about the ECT sensor, not sure which one that is on a 22RE since it's reversed from the 3VZE. I think it's either green or gray in color on the water bypass on the back. That little thing can cause a host of silly issues if it's going bad.

 

Did some major troubleshooting work today. I was able to rule out many of the potential suspects with a good degree of certainty. Here's where it stands now:

- When warm, the truck will not start. The ignition is good -- a grounded spark plug shows a bright blue, hot spark. Cracking the banjo bolt at the cold start injector shows fuel pressure when key is in start position so fuel is flowing at least, not sure of correct pressure.

- When cranking hot, a small shot of starting fluid down a vacuum port will start it right up with no problems and it will idle and run fine. I can also put 12V across the cold start injector and it will start hesitantly. The issue is clearly lack of fuel delivery.

- At this point I can't tell if the fuel injectors are firing in this hot-start condition. Their resistance and the injector resistor resistance is all in spec (I even put my stock Denso plugs back in just to be sure). I'm not sure the best way to check that they are indeed firing.

- I am also suspicious that the fuel pump is getting weak. I will try to check the fuel pressure soon and may swap another pump on to check. Would a weak fuel pump cause these starting problems? And why would it only occur when the engine is hot? Fuel pressure not high enough to prevent vaporizing of the fuel in the lines?

 

From what I understand, yes. Low PSI would take a long time for the lines to pressurize and could result in poor starting conditions. Like others were saying, it might vaporize the fuel from the heat.

Did you check the ECT sensor?

 

Yes, I had an OEM ECT sensor handy. I checked its resistance vs temp in a pot of water. All in spec, no dead spots. I swapped that in with no change.

 

Well then, I'm officially out of ideas! Most non-start issues are fixed by repaired bad wiring, replacing the VAFM or the ECT sensor. But you've checked all that... not sure what to tell you. I leave it up to more qualified Yotatechers than me.

 

mechanics stethoscope touching the injector, $3.99 at harbor freight: http://www.harborfreight.com/mechani...ope-41966.html

see if the injector is clicking while the engine is being cranked over.

someone also posted that you can do the same thing with a piece of vacuum hose(?)