f engine problems. (1 Viewer)

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Feb 6, 2022
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Location
Colorado
Hey fellow cruiser heads. About a year and a half ago, I bought a 1970 fj40, for what I thought was a steal. Turns out that the engine had just about as many problems as my Ex-Girlfriend. My dad, an experinced mechanic has owned many different classic cars over the years, but this silly little I6 is giving him more trouble than he has ever had. Long story short, we have fixed many different problems with the engine, but it still isnt close to being 100%. I will try to list exaclty what we have done to the engine over the course of ownerhsip. Then I will list what is still giving us trouble.

Fixes:
1. New battery
2. Fixed many different wiring shorts
3. New fuel and vaccum lines
4. New fluids
5. New HEI Distributor
6. New plugs and plug wires
7. New fuel Pump
8. Newly machined head from Rev Motors in Denver Co.
9. New head gasket, valve cover gasket, water pump gasket, and manifold gaskets
10. New water pump
11. New hosing
12. New JT outfitters header
13. Correct valve lashe dimensions
14. Tried two different new carbs
15. Timing is dialed in at about 7 degrees BTDC
16. Made sure cam gear hadnt slipped a tooth


We did not just start throwing parts at it, but rather diagnosed the problem, then proceeded to fix it with what made the most sense. For example, The old distributor was super wobbly and wouldn't make good contact for their to be good spark. We have fixed many different problems but something still ain't right.

The current issues right now are :

1. Even when warmed up, engine does not like no choke. When choke starts to open up to bring more air into the carb, the car wants to die. This feels like a vaccum leak, however, we sprayed and did not find one....

2. The mixture screw has no effect on the idle. We had the car idling with the screw about 1.5 turns out from all the way in, then kept turning it. No change in idle took place.

My thoughts are either an incorrect carb, and or possibly warn down cam lobe for intake valve, and or a tricky vaccum leak.


Sorry for the lengthy post, but she needs to see the road again. I appreciate you reading my description and would love you're thoughts.



Thanks, Andrew
 
Does a 1970 40 have power brakes? I dunno, but if it does, make sure the booster diaphragm isn't ruptured. Where did the carburetor come from? Has it been overhauled? I switched to a 2300 series 2bbl Holley (on a Downey adapter) and have had zero issues.
 
Have you taken a vacuum reading?
What carb is on it, what carbs have you tried? Where is the fuel level in the sight glass (assuming aisin carb). If aisin carb, is it correct for the year?
Pics would help too.

Vacuum leak is where I would lean with the symptoms (or incorrect carb/settings). I would start by capping or pinching off all vacuum sources from the intake manifold: cap where the 4wd shift goes to, cap base of carb for distributor, cap any other carb ports, cap manifold port to power brake booster (if one is present: not stock for 1970 depending on month built?)
I’d start there and get a vacuum reading; you’ll have to use one of those capped ports for vacuum gauge.
 
1. Even when warmed up, engine does not like no choke. When choke starts to open up to bring more air into the carb, the car wants to die. This feels like a vaccum leak, however, we sprayed and did not find one....
Assuming the stock carburetor, does Idle solenoid click when you turn on the key?
 
Let's see a couple pics under the hood to rule out anything obvious. It will be helpful to see what carb and distributor you have and how things are connected.
 
Does a 1970 40 have power brakes? I dunno, but if it does, make sure the booster diaphragm isn't ruptured. Where did the carburetor come from? Has it been overhauled? I switched to a 2300 series 2bbl Holley (on a Downey adapter) and have had zero issues.
Mine does not have power brakes. I forgot where we ordered it, but i belive it's one of the Aisin Carbs.


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Let's see a couple pics under the hood to rule out anything obvious. It will be helpful to see what carb and distributor you have and how things are connected.
Just uploaded some pics in my reply to DougAustinTx
 
Does it have an idle solenoid? It should be just below the pivot bolt for the accelerator pump arm on the valve cover side.
 
The electrical connector on the engine side of your carburetor is the one for the idle solenoid, it needs to be plugged on something switched with ignition.
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The correct cable should pass through the firewall in the same hole than the choke (and the cable for temp sensor also).
You have a cable getting out of this hole and going in direction of the master cylinder, is-it plugged to something?
1644250154161.png
 
Have you taken a vacuum reading?
What carb is on it, what carbs have you tried? Where is the fuel level in the sight glass (assuming aisin carb). If aisin carb, is it correct for the year?
Pics would help too.

Vacuum leak is where I would lean with the symptoms (or incorrect carb/settings). I would start by capping or pinching off all vacuum sources from the intake manifold: cap where the 4wd shift goes to, cap base of carb for distributor, cap any other carb ports, cap manifold port to power brake booster (if one is present: not stock for 1970 depending on month built?)
I’d start there and get a vacuum reading; you’ll have to use one of those capped ports for vacuum gauge.
We havn't taken a vacuum reading yet, but thats a good start. We tried the original carb but it was in very bad shape, and we didn't think we should have taken the time to rebuild it. Then we have tried two of these Aisin carbs(pictures in my reply to (DougAustinTx.)


The fuel level is about halfway in the sight glass. Its interesting because i found my carb on amazon, when trying to find the exact one i have. It matched perfectly, but the descrption reads" 1969-1987 carb for toyota 2f" Which doesn't make any sense with when they switched to the 2f. So maybe the carb we have is meant for a 2F.But a carb is a pretty basic function, so i cant imagine a different carb would drastically effect how its running. Maybe im wrong on that.


We have plugged all of the vacuum sources, including the goofy vacuum actuater(which i belive was only prodcuded for 9 months). I will try to get a few readings tonight. Thanks
 
The correct cable should pass through the firewall in the same hole than the choke (and the cable for temp sensor also).
You have a cable getting out of this hole and going in direction of the master cylinder, is-it plugged to something?
View attachment 2917315
No but for awhile we did have it plugged into the carb in the place youre talking about. We thought it was an electric choke but maybe not. I will try messing around with that tonight, but I beleive we have had the plugged in, and didn't change much.
 
That looks like one of the Chinese knock off carbs. Definitely get that fuel cut solenoid connected. The early 70s carbs had mechanical vs vacuum secondaries. Looks like it has the non usa ported vacuum tube in the throttle body (next to the air/fuel screw on the valve cover side) is that capped off? Does your distributor have vacuum advance?

Did you keep the original carb?
 
No but for awhile we did have it plugged into the carb in the place youre talking about. We thought it was an electric choke but maybe not. I will try messing around with that tonight, but I beleive we have had the plugged in, and didn't change much.
Try connecting it directly to 12V, it should click when connected/disconnected, and run your engine like that to see if things are getting better.
When this solenoid is not connected to 12V it literally blocks your idle circuit so the engine doesn't receives fuel in idle. When you pull the choke you also put some gas and so get out if the idle circuit, which explains why it runs only with choke.
 
Try connecting it directly to 12V, it should click when connected/disconnected, and run your engine like that to see if things are getting better.
When this solenoid is not connected to 12V it literally blocks your idle circuit so the engine doesn't receives fuel in idle. When you pull the choke you also put some gas and so get out if the idle circuit, which explains why it runs only with choke.
wow very interesting and helpful. Ill give it a shot. Thanks
 
That looks like one of the Chinese knock off carbs. Definitely get that fuel cut solenoid connected. The early 70s carbs had mechanical vs vacuum secondaries. Looks like it has the non usa ported vacuum tube in the throttle body (next to the air/fuel screw on the valve cover side) is that capped off? Does your distributor have vacuum advance?

Did you keep the original carb?
Ok i will get that connected. And yes the ported vacuum tube is plugged currently. The distributor does have vacuum advnace, but we havn't plugged it because it shouldn't matter at idle if im correct. I will still plug it anyways.

No we sadly did not keep the original carb.
 
Look at the PCV valve (red hose), I had a very similar issue a couple of years back, PCV was leaking excessively at idle, causing a vacuum leak. I was lucky and found a new PCV on e bay that threads into the oil fill. If you need to, use a PCV from a newer vintage and splice into the hose.
 

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