Been getting some work done on my 1987 Toyota Pickup 4x4 -- had some carb issues fixed but on my last test drive, the truck completely shut down at lower speeds.
Had it towed back to the shop where my mechanic says he noticed the truck has both an electrical and mechanical fuel pump and that he turned off/disconnected the electrical one. The previous owner said the truck had the electrical pump when he bought it but then "swapped" to the oem mechanical pump after. My mechanic says he can still see both installed and is baffled as to why someone would do that, as they would just bottleneck.

I'm honestly baffled myself and wont have time to go see it until the weekend but I assume this is most likely the issue. Any ideas on how to proceed?

 

If it were me, I'd get rid of the electric fuel pump. Replace the pump, hanger, etc, with just the tubes that go into the tank. I am not certain just how many there should be, but I know for sure there's at least 3. The pickup, the return line, and the vapor return. I think that the electric, not running, is probably restricting the volume of fuel flow the mechanical can draw out of the tank. Maybe. I could be wrong.

Another possible problem you may be having is the float valve is either clogged slightly, or the float isn't properly aligned. That may be why the carb is running out of fuel. You can watch the sight glass on the front of the carb, and run the engine at various RPMS, and make sure the level in the glass remains in the right place (between the two points on the glass). If it doesn't, there's a problem with either the float, it's alignment, or the float valve.
You might also have a clogged jet. It only takes a tiny little speck of dirt to clog up one of the jet's holes. Fortunately, the carb rebuild kits are quite readily available, and the carb is actually pretty easy to rebuild. I believe you only need to pull the top half of the carb off, only a few screws, take out the jet and clean it up, IF that's the trouble.

Good luck, and keep us up to date on the progress!
Pat☺

 

I agree with 2ToyGuy, replace the electric fuel pump assembly with the proper pickup tube for a carbureted truck. The in-tank electric fuel pumps came on EFI trucks, and mechanical on carbureted trucks. If the electric pump is external, then someone added it later and it should just be removed. If it is the EFI in-tank pump, it might have created enough pressure to blow out the diaphragm in the mechanical pump if it could not return fuel to the tank fast enough. Check the emissions sticker under the hood. If the truck was originally EFI, someone may have swapped it to a carburetor and that will be a problem with California smog. If that is the case, then hopefully the EFI wiring is still there and you can convert it back.

 

Thanks for the reply. I'm going to take a look this weekend and see If I can completely strip any remains of the electric pump and get it running. First thing that came to mind was that the it was restricting the volume of fuel flow so glad to see you mention it. I'll check the valve and jet. Appreciate the help, ill make sure to update how it goes.

 

Ive checked before and its originally a carbed truck. Im not sure where the electric fuel pump was positioned but the mech did mention something about a bad diaphragm and having to maybe swap out the mech pump for a new one. I'll make sure to check the specs and see whats the deal. Thanks

 

If the electric is an aftermarket job, just follow the fuel lines. You'll find it eventually. Just pull it out, and either replace the fuel hoses, or put a jumper into the lines to replace the pump. Just a short piece of tubing that fits the hoses. All pretty easy to accomplish.

I've replaced the mechanical fuel pump in my pickup several times over it's long life so far. Very easy. Heck, the hardest part was breaking the fuel lines loose. They really grab the metal fittings over time. Thankfully, they're right out in the open on top of the pump, and easy to get to. I grab the fuel lines with a pair of pliers, the rounded part, and give them a few twists, and they come loose easy after that.
I've found that a thin layer of Vaseline on the inside will keep them from grabbing the metal fittings nicely. Or you can put it on the metal fittings, then slip the hoses on. Same effect.
Make sure you use an OEM fuel pump. They last the best I've seen so far. I can't recall the OEM name, but it's probably Denso, Aisin, something like that.

Good luck to you!
Pat☺

 

Turns out the electric fuel pump was added by a previous owner. We were able to remove it completely and leave just the mech pump--not entirely sure what my mechanic did but it now turns on and runs. I believe the gas flow was just being restricted. The truck still has a flat spot when it warms up but I think we were able to track the issue to a broken valve (I believe its the BVSV VSV -- its brown with 3 valves sticking out). I was able to find an oem replacement valve but that wont arrive for another few days. I'll update if that gets the job done, once I get it smogged. Thanks for the help!

 

Thanks, we were able to completely remove the electric fuel pump. Using an aftermarket mech pump now and it seems to be doing its job for now. Ill look for an oem and swap that out later. Just need to find whats causing a flat spot when the truck warms up for now.

 

AFM, and/or TPS are both good possibilities. Check them both through their entire range of motion for the correct ohm values. IIRC, they should be in the FSM. The TPS quite often can cause this problem, especially if it has dirt or corrosion in the wiper's range. Worth a look.

Pat☺

 

Without looking at a vacuum diagram, I think the BVSV switches between the AAP and the EGR as the engine warms up. If the EGR side is broken, it will cause a vacuum leak at part throttle when the engine is warm, so that could be the problem. An Improper repair was done by someone on your truck, so there might be more. They probably messed with the vacuum lines if the BVSV is broken, so double-check all the vacuum line routing when you replace it. If that does not fix it, let us know exactly where the flat spot is and we will figure it out!

I agree to get an OEM fuel pump (as well as most other parts). Quality aftermarket parts these days are getting hard to come by. I believe OEM is Kyosan for the carbureted mechanical pumps and Denso for the EFI electric pumps.

 

You've lost me. Im not familiar with those acronyms

 

Yea, we looked through all the hoses and this seems to be the only thing giving us an issue. We made sure to test the valve and it never switches so were going to start there. Wish I had a diagram of how the vacuum and gas lines should all be arranged but were just checking as we go. Ill definitely update you guys when we replace the BVSV. Im already looking for a new oem pump--hopefully I can find one.

 

AFM=Air Flow Meter. The device attached to the box that holds the air filter.
TPS=Throttle Position Sensor. The electric device attached to the throttle body. It is on the right side as you look at it from the front. It has a plug that goes in the bottom. When the throttle cable pulls on the big blade in the throttle body throat, it allows more air into the Throttle body. As is changes position, it's central shaft changes the position of the wiper in the TPS. Essentially, it tells the ECU what the position of the throttle is at. Frequently, dirt or corrosion can build up on the electrical contacts in the TPS. Thus, it tells the ECU the throttle is at a different position than the amount of air the throttle plate, or blade, is allowing in.
IIRC=If I Recall Correctly. Self explanatory.
FSM=Factory Service Manual. If you can't find a paper on, do a search and you can probably find one in PDF format.

Unfortunately, I'm an idiot, and forgot you're trouble shooting a carbed truck. My pea-brain went straight to 22RE, and forgot we talking a 22R. DER! I apologize profusely. Forget the first two entries above. Just Ignore them. Nothing to see there. Move along. Move along...

The 3 port BVSV (there's 2 BVSV's, one with 2 ports, one with 3) has 1 port, the top one, that goes to the carb, and splits into 2, one goes to the Choke Breather, the other to the three port vacuum source on the side of the carb. 1 port, the second down, goes to the carb, and splits into two, one straight to a vacuum source on the side of the carb throat, the other to the Choke Opener. The bottom port goes straight to the AAP.



I used red arrows to point at the various devices the BVSV feeds. I'm really crappy at working with pictures, so I didn't uses colors to trace the lines, but I think you can do it yourself. If you would like the complete picture this came from, I can post it for you. It might help you trace out the various vacuum lines. There's a bunch of them!

Hope this is slight help...
Pat☺

 

Good post with the vacuum diagram. It looks like I goofed earlier and mind got the 2 BVSVs mixed up. After looking at 2ToyGuy's vacuum diagram, the 3 port BVSV does not control the EGR like I originally thought, but I can see how it would cause a flat spot. If it is stuck in the cold position, the AAP would give too much fuel for a warm engine, causing a hesitation on acceleration. Hopefully the extra fuel did not hurt your cat too much, assuming you need to smog it.

 

If you want, I can put up the diagram of where the 2 port BVSV goes. I didn't cause you were talking about the three port one pretty exclusively.
I can also put up the entire diagram that little chunk I put up is from. If I do, It will be a little hard to read, though. It might be OK though.
Let me know

Good luck!
Pat☺

 

Bit of an unexpected update.

We got the new three valve BVSV and it fixed the flat spot BUT we encountered a second issue. Mechanic friend said he got the truck running/idling great but when he took it out for a 20mile drive, the truck suddenly lost power and died. We got it towed back to the shop where it started up again with no issue. We thought it would be safe to swap the aftermarket fuel pump incase it was damaged and I took it home for a test run. On the drive back (about another 20+ miles) the truck died on me once again. Same thing, I was in third gear when I suddenly had no power on the gas and I drifted to the side until it completely cut off. Both times when it died before, we got it towed back to the shop and when it arrived to the shop the truck would turn on again--so this time I waited an hour and then put in in neutral and shook the truck a bit. It turned on and I drove it fine for another 10miles home.

At this point Im not sure whats wrong. Mechanic friend also mentioned the float valve so I think ill be taking it back and having him take apart the carb for the 3rd time. He did show me a picture of the carb when he first took it apart and it was really rusted/corroded but he swears by the work he put into "rebuilding" it with parts from a donor carb and a carb kit. It wasnt a professional job but he said he tested it.

So yea, any advice would be fantastic.

Ill be checking if the float valve is clogged at all or if the float isn't properly aligned (or a clogged jet) but now im considering buying a whole new carb IF I can find the proper California legal oem version.

Really appreciate the help guys. Especially that diagram.

 

I believe the new BVSV fixed the flat spot issue. I havent examined the cat but Ill take a second look since I do actually need a smog.

 

Thanks, the entire diagram would be nice! I dont think the current issue is related to the BVSV but it would be nice to have.

 

Glad the BVSV fixed the flat spot. I had a truck that did similar to what you are describing. It would run great, then it would start to cut out and die, but I could always get it to restart. It turned out the carb was overflowing fuel into the secondary barrel slowly, then it would flood the engine and stall it. Fully rebuilding the carb, including a new float, fixed the problem. If the carb was really corroded, it might need to be completely torn apart, soaked in solvent, and cleaned thoroughly before it is put back together. With the air cleaner off and the engine running, you can look down the throat and make sure no excess fuel is overflowing into the engine. Check the sight glass as stated above, especially when the engine is acting up. Other things that come to mind would be gunk floating in the gas tank and plugging the fuel suction tube, or an ignition component that is shorting out when it gets warm. The coil, igniter, and distributor pickup would all be possibilities.

Here are some quick tips that might help:
-If the truck will restart after stalling by holding the accelerator to the floor while cranking it, that points to a flooding issue.
-If there is no fuel in the sight glass when the engine stalls, that could be a clog in the fuel system anywhere from the tank to the needle seat in the carb.
-Checking for spark when the engine quits could rule out an ignition problem.

 

Here ya go
As you can see, the two-port BVSV is what works the EGR system.
If the three-port went bad on you, there's a pretty good chance the two-port may have failed as well.
It's also possible that the threads of the BVSV have gotten a corrosion build up on them. Since the valve uses what it's screwed into as part of it's circuit, if there's any electrics involved, corrosion on the threads is a problem. Big problem. It doesn't look like there's any electrics involved with the two valves in question, but that's something to be aware of. Easy enough to clean off with a brass wire brush. NOT steel! That can damage the aluminum threads badly.

Good luck. I hope everything goes well. If you want, I can take a pic of the vacuum diagram under the hood in MY 22R powered, 2WD, pickup, to help you route the vacuum lines correctly. If you want. I think the diagram should be pretty close to your truck's engine, but I can't promise.
Pat☺