Engine hesitation (1 Viewer)

[Groucho263]

So, on my '75 with Aisan carb, I have a return spring here (below). Make sure that you have some wiggle on the accelerator linkage so that the adjustment rod does not define your idle speed. There is a little wiggle here and the linkage springs back to the stop. I think this one is ok.

View attachment 2477928

Also, I use flat washers under lock washers for the M8 carb studs. I notice that they get kinda loose between assemblies, and it can't hurt. Ok, I'll get the washers installed.

If the EGR valve does not close, then it will be really hard to tune, because EGR only really works when the engine is hot, and it is above idle on the throttle. I don't like old smog equipment. New smog equipment is good, EGR is good technology for a gasoline engine, but after the exhaust goes thru Toyota's exhaust cooler, it forms condensation akin to the stuff out of a winter tailpipe, and they rust so they don't totally close. Your engine has good vacuum, IIRC, but your fuel charge might be off with the proper mix of air (vacuum leak), or exhaust gas (good only when needed). I don't claim expertise on the EGR subject, as mine is stashed in the crawlspace, but it is a hunch. Do I even need the EGR? Can you remove it and make the engine run better? Based on the condition of the ECV and other things on this rig, that the EGR is probably not closing (or operating correctly).

Let's say that the slow oxidation has compromised the electrical ground for the idle cut solenoid. I was thinking that you check that there is conductivity from the carb to the engine/chassis with a multimeter. At the solenoid connection there is 12V with the key on.

Off subject, but I thought that the City Racer carb needed a spacer for that air cleaner height? Is it a '75 USA air cleaner assembly? I'm not sure...I didn't get one with the carb. Could it be sucking air? I believe that's a 75 air cleaner assembly, but not sure.

Took it on another test drive (still gets too hot...can a thermostat go bad that quickly?) So...the engine is much better, but not quite right. In 3rd gear there is still some hesitation. I did this: Just for giggles, run a wire from the + side of the battery to the + side of the coil without much noticeable change. But I will say from before this thread to now, there is a lot of improvement. Could I still need to fine tune adjust the timing? Is it the EGR?

By the way...thank you for spending this much time with me. I love this place and hope to someday help out others like you guys are. Thank you.

 

[Dizzy]

You might need a new radiator?

Jim C. can help with the EGR. Products

 

[Groucho263]

You might need a new radiator?

Jim C. can help with the EGR. Products

Radiator is brand new. I’ll get in touch with Jim.

 

[rsnellie]

Didn’t see if someone mentioned this, but with the electric fuel pump are you sure the pressure isn’t too high and over powering the float in the carb causing a flooding/rich condition after running?

Second are you sure the float level is set correctly? The fuel should be I believe halfway in the glass window on the carb at all times. If it’s low after running then it’s going lean because the fuel isn’t getting to the carb fast enough or the float is set too low. If it’s completely full then the float is too high or the electric pump is over powering the float causing it to have too much fuel. Both of these would cause performance problems after running.

 

[Dizzy]

The float drop is important too. In my case, it caused the bowl to overfill.

 

[rsnellie]

The float drop is important too. In my case, it caused the bowl to overfill.

Exactly what I suspect in my post above. Fortunately with the glass site window it should be a quick verification.

 

[Groucho263]

Exactly what I suspect in my post above. Fortunately with the glass site window it should be a quick verification.

Ok, I'll have to check this out in a couple days...have to go to work tomorrow (back Thursday). I do remember before I added this thread that I looked at the sight window and it was full (not half), then I ran the motor and the level was below half. I am not 100% sure about this though and will have to test it. The way it's rigged up from the PO was from the fuel tank to a fuel filter to the electric fuel pump to another fuel filter to the engine driven fuel pump to the carb. The return line to the fuel tank from the engine driven pump was capped off. I removed the first fuel filter but left the rest of the setup. I could try to bypass the engine driven pump...or bypass the electric fuel pump. Let me see what the sight window does as I run it.

 

[Dizzy]

I could be wrong about this, but the float height setting seems to meter the level of fuel in the sight glass. The float drop setting seems to meter the volume (and pressure) of the gas at the carb inlet.

I had my drop setting off, and it would be fine in the site glass in the driveway, then I was driving around, and my O2 sensor readout suggest super rich all of a sudden. I pulled over, and the bowl had overfilled. I got home and it was fine in the site glass again. I pulled the air horn off the carb, fixed the float drop and haven't had the problem since.

Only one, correctly pressured, pump is to be installed, if I am reading this correctly. Two pumps create more pressure.

 

[FJ40Jim]

I could be wrong about this, but the float height setting seems to meter the level of fuel in the sight glass. The float drop setting seems to meter the volume (and pressure) of the gas at the carb inlet.

Only one, correctly pressured, pump is to be installed, if I am reading this correctly. Two pumps create more pressure.

You are right, wrong, right.
Float height is the fuel level in the bowl (and glass).
It needs to be on the glass to run, but it doesn't effect running if it 2mm above or below the middle

Float drop has no effect on anything in normal operation. If the float drop is way too low, the float could drop so far that the needle falls out. Float drop way too high would prevent needle from opening.

Yes, pumps in series add pressure. Pumps in parallel add volume.

 

[billmc]

You are right, wrong, right.
Float height is the fuel level in the bowl (and glass).
It needs to be on the glass to run, but it doesn't effect running if it 2mm above or below the middle

Float drop has no effect on anything in normal operation. If the float drop is way too low, the float could drop so far that the needle falls out. Float drop way too high would prevent needle from opening.

Yes, pumps in series add pressure. Pumps in parallel add volume.

and if the diaphragm goes on his stock pump he gets to have extra gas in his sump

 

[John Smith]

I noticed you are missing a key bushing in your throttle linkage. See the yellow arrow.

 

[Groucho263]

I plan to work on this tomorrow and have a couple questions based on the posts above.

- Do I need to disconnect the EGR valve and put a plate into the manifold? If yes, do I disconnect the EGR on the other side? I also assume if yes, that Jim can help with that.

- Do I leave both fuel pumps inline or disconnect one and only run on one? If yes, the engine driven pump seems to be working...is that the one to keep operating?

- Do I need a gasket between the air filter and carb? I assume get that from SOR?

- Do I need that bushing that @John Smith is referring to? If yes, I would assume get it from SOR?

- What do I do about the fuel in the site glass?

Thanks guys!

 

[Dizzy]

I thought that Jim C. had an intake manifold cap, and an exhaust manifold cap on his website. Do what you want with the EGR, I just have a hunch that with enough age, these things might leak, causing a problem with engine performance.

A carburetor must have the correct fuel pressure. Just one fuel pump is needed. Because I don't know better about the condition of what you have, the best advice is a new Aisin fuel pump. Otherwise, for troubleshooting sake, you need only one fuel pump, your choice which one, they are both not OEM. The engine driven pump, if leaking on the inside, will fill the crankcase with gasoline, and could leave you with a mechanical nightmare. The electric fuel pump is a bit of a hack. They can work in some situations.

It looks like you might need the spacer from City Racer to run your shorter carb on a USA air cleaner? There is an air leak that I can see in the image above.

You need the fuel level to be somwhere in the site glass

 

[rsnellie]

I plan to work on this tomorrow and have a couple questions based on the posts above.

- Do I need to disconnect the EGR valve and put a plate into the manifold? If yes, do I disconnect the EGR on the other side? I also assume if yes, that Jim can help with that.

- Do I leave both fuel pumps inline or disconnect one and only run on one? If yes, the engine driven pump seems to be working...is that the one to keep operating?

- Do I need a gasket between the air filter and carb? I assume get that from SOR?

- Do I need that bushing that @John Smith is referring to? If yes, I would assume get it from SOR?

- What do I do about the fuel in the site glass?

Thanks guys!

me personally I’d get rid of the electric pump. The mechanical fuel pump was a system Toyota believed in and In my opinion for good reason. It’s been a long time since I’ve messed with the fuel system in a 2f, but I believe the mechanical fuel pumps push less than 10psi. The wrong electric pump could easily produce way to much. For example the one I use in my 3fe conversion does well over 50. If you are worried about fuel leaking into the crankcase just verify oil level hasn’t gone up on the dipstick. If it has, change that oil and get a new pump immediately before starting it again. Gas dilutes the oil and makes it ineffective as a lubricant and protectant.

I do however wonder why they installed 2 pumps. If the mechanical pump isn’t working correctly it may not be pumping enough volume. Perhaps that’s why they tried this fix, but considering it’s not working tells me they may have just been throwing parts at it rather than diagnosing it.

1. I’d bypass the electric pump and see what happens.

2, start the car and verify the fuel level in the carb. Like mentioned above it will fluctuate a little, but it shouldn’t be completely full or completely empty. If it’s completely full it’s probably flooding and float may be set wrong.

3. I’d also wait for it to start running poorly then pull a spark plug and see if it’s wet. At this time I would also verify good spark by holding the Plug thread to an engine ground and look for a nice hot spark. Failing coils tend to work when cold and degrade performance as they heat up. Just because one is new doesn’t mean it’s good. I’ve had many bad coils out of the box. I know you’ve replaced it a few times already, does your system use a condenser?

4. this should help you determine if you should be chasing a fuel or spark problem. Sometimes it could be both.

If you are having problems with it overfilling the carb the adjustment is super easy if the float setting is wrong. It’s also easy to swap the fuel pump. Try some of these trouble shooting tips and perhaps you can get the experts a little more information to help you narrow down your problem. There are people on here that have dealt with pretty much every scenario. My technique is my process, but I’m no expert and I’m sure someone else could chime in with a better process and more experience.

After this, order the parts you’re missing and need.

 

[Chuckha62]

Here's what I did solve my issue. I hooked up a volt meter to the Pos. side of the coil and drove around. Sure enough, when it would start to act up, I'd look over and see the voltage fluctuating, sometimes as low as 5V. With an internally regulated coil, that means it was STARTING at 5V and dropping through the coil. This is an easy check. Once I SAW it happening, I jumpered around the switch and it stopped dropping voltage.

 

[Groucho263]

I thought that Jim C. had an intake manifold cap, and an exhaust manifold cap on his website. Do what you want with the EGR, I just have a hunch that with enough age, these things might leak, causing a problem with engine performance. The site you sent me to is for Tim White...TLC Performance? Is that different than Jim C? I'm going to fix this spacing on the carb and fuel pump thing before I do this...but this is the next step. It does make sense that that EGR is bad since everything else on this thing has been bad.

Going to bypass the electric fuel pump and run the engine driven one...I ordered a new one and should have that in a couple days...once I get it, I'm going to install that. I'll do the bypass tomorrow.

I got a spacer and gasket from City Racer coming for the carb.

@rsnellie ... spark is good...did all that trouble shooting last week. Had to set the timing to about 14 btdc...and have good spark. park plugs are mostly good...see previous pics. Fuel though, and the float issue, I'll work on this tomorrow. Might be an issue. If I have to adjust the float, I'm sure I can find how to do that on here.

@Chuckha62 I'll work on that after the other steps above. Thanks for the additional info...I'm learning a ton.

 

[FJ40Jim]

Here are links to the
EGR block off plate,
and gasket,
on the TLC performance web store.

 

[Groucho263]

Here are links to the
EGR block off plate,
and gasket,
on the TLC performance web store.

Thanks Jim...sorry about being the newb...I just ordered a set for my FJ40...but had a quick question. One of the lines at the manifold goes to the PCV and the other to the EGR. What the heck do you do with both of those once you put the block off plate in place? Are there plugs for those...if so do you sell them? Thanks in advance!

 

[FJ40Jim]

The PCV plate & hose should remain in the side of the intake manifold.

The EGR block off plate goes at the other end of the EGR where the flanged pipe comes down off the exh manifold.

I do make a block off plug for the threaded fitting where EGR is connected to intake manifold pipe, but can't find a pic ATM.

It's similar to this brass one,
but machined from a steel bolt.

 

[Groucho263]

The PCV plate & hose should remain in the side of the intake manifold.

The EGR block off plate goes at the other end of the EGR where the flanged pipe comes down off the exh manifold.

I do make a block off plug for the threaded fitting where EGR is connected to intake manifold pipe, but can't find a pic ATM.

It's similar to this brass one,
but machined from a steel bolt.

Ahhh...ok. So the block off plug for the threaded fitting to the intake manifold...is there a similar plug for the EGR cooler? I'm assuming the whole EGR gets removed?