Tercel Bucks and Dies under load

[Mad_Marx]

After recently replacing my Toyota Carb with a Weber, I also ended up replacing the intake/exhaust manifold gasket, while I was at it I removed the EGR and plugged the hole in the exhaust and intake, and verified PCV venting and function (the pcv valve is relatively new, less than 10,000 miles on it) It was running like a champ for a few weeks, but recently started to buck and lose power under load (i.e. in 3rd gear trying to accelerate or driving uphill), then eventually it will die. When trying to re-start after the issue occurs, pumping the throttle will make it die. This issue occurs when the engine is Dead Cold and/or after it's warmed up. It idols fine and the RPMs stay at a steady smooth 800, with no load on the engine it will idol indefinately without issue. When this first started occuring it was on a day we were having 100+ Temps and I was fully loaded for camping with the AC Running, my first thoughts were Vapor lock (it felt like Vapor lock). After getting it home and duplicating the problem with a cold engine in 70 degree weather I no longer suspect vapor lock, but it definately feels like fuel delivery. I have a NEW Weber 32 DGES, New Carter mechanical fuel pump, New fuel filter, and a New fuel pressure regulator that is set to 5 lbs and had been running just fine at 5 lbs. I tried turning it up to 5 and 1/2 lbs. with no change to the driveability issue. I also swapped the Carter fuel pump for the old Toyota pump (no change in issue). I have also recently replaced Plugs (bosch Platinum +2 plugs), wires (Borg Warner 7MM), cap, rotor, and ignition coil (all Borg Warner parts). I have checked for vaccum leaks and checked all wire harnesses for exposed or shorted wires and/or loose connections. I also checked the Gas Cap vent tube and Gas cap when issue is occuring. Unable to find anything bent broken, missing, damaged, missaligned, rotted, or otherwise obviously broken.
Anyone ever had problem with a new Weber or a New fuel pressure regulator (the cheap Dial kind)??? It sure feels like a fuel delivery issue, but could this be related to something else? I tried disconnecting switches to the charcoal canister, AC, and O2 sensor while the car was idoling with only minor changes to the idol (i.e. it ran a little rough but did not choke and die like it does when I'm on the road and the problem rears it's ugly head). I'm running out of ideas, any help is appreciated.

[splatterdog]

I'm not sure about the DGES but the DGEV takes half that fuel pressure. I would also verify what your pressure really is with a gauge. Fuel filter good? Can you see if it's full of gas? If it's not full or very close to it, it might be clogged or might have a restriction between filter and the pickup in the tank.

If the carb is delivering too much fuel you should smell it. If not, maybe not enough. With the air cleaner off you should see a solid squirt of gas come out by the top of the carb's opening when the throttle is opened.

I had a "dial" type regulator rupture after about 6 months. Wife dumped over half a tank on a hot engine that very hot day. New one has been good for a while now and was relocated to the fender for safety reasons and I'm sure has lasted longer with less heat. It was zip tied to the brake booster vacuum hose. I've seen others tucked right in between the carb and valve cover. Bad idea!

Did this happen after the tune? I've fixed a couple cars by just taking out the new bosch plugs. I have also noticed the plus 2's and 4's are horrible for fouling so if your valve seals aren't good you will have trouble much faster than a conventional single ground plug. Iridiums are the way to go! NGK or autolite if you want to save a few bucks.

[Petros]

sometimes when the coil or electric ingiter get marginal, they will run okay cold but start cutting out as they warm up. Eventually they cut out all the time, and than will not work at all. These are all built into the distributor. If you have a U-pull-it type of yard nearby just get a spare distributor assembly (about $12 typically) and swap it out. the fastest check you can do. Otherwise follow the FSM procedure for testing each component.

The quick check would be to drive it until it cuts out, and than check for a good spark by pulling a spark plug wire and hold it 1/4" from a ground while someone cranks the engine. It should be a strong bluish white spark. IF you get a weak or yellowish spark, it is the ignition system. I would not necessarily jump to fuel starvation just because you have an altered system.

But after it is cutting out would be a time to check the fuel supply too. Pull the air cleaner, look in the carb and pump the throttle, if you do not have a stream of gas squirting, in it is starved. But also as noted, you should check for overpressure/too much fuel. excess fuel pressure will overpower the float valve and flood the engine. If you smell it, or pull the spark plug and it is soaking wet, you have excess fuel going in the engine.

Good luck.

[Mad_Marx]

Brand new fuel Filter, full tank of gas (91 Octane)
Did the tune up After it started having problems with no change in performance after the tune up. I had the parts before the problem started, so since the car was just sitting in the driveway I figured it couldn't hurt. The OLD plugs, wires, cap, and rotor had about 30,000 miles on them so they were due. The used plugs had NO signs of fouling and only minor ash deposits on the outsides of both electrodes. All plugs showed roughly the same amount of deposit and appeared to be wearing evenly on the electrode.

Replaced the ignition coil (yes it's built into the top of the distributor, but serviceable) and while I had it apart I removed the distributor and checked for play in the shaft and any signs of burnt wires, worn parts, corroded connectors, abrasion to wires or moving parts, or loose wiring. None found. I should also add that the dust seal was amazingly in tact and underneath the cap was SPOTLESS.

No sign, smell, sight or otherwise of too much fuel, flooding, or overpressure. If anything it was suspiciously under-fed when it acted up I would let it die, removed the air filter and with the ignition off, pumped the throttle by hand while looking down the barrels. Barely any fuel squirting, that tells me the accelerator pump was near empty and float bowl along with it.

I got online today and looked up the cheap spectre dial type fuel pressure regulator I had purchased, found some not so flattering reviews and a series of people who had had the same problem or worse with the regulator not putting out enough pressure even when fully opened up.... see some here:

http://www.amazon.com/Spectre-2517-Chro ... B000CQ46H0

One review mentions 2psi measured by gauge even with the thing cranked all the way up, I guess the little sticker on the thing should be changed from "Approximate" to + or - 5 to 10 psi ???? what a piece of crap!!!! Mine was mounted between the pump and the carb, about 2" away from the valve cover and head, wrapped with a radiator hose 1/4" shield and zip tied to the throttle bracket to stop vibration. If that's enough head to kill the thing, they need to re-engineer that product.

I couldn't find a gauge or a fuel pressure regulator in town today, so for a test I removed the regulator and ran it straight from the pump to the Carb, ran it long enough to get good and warm (about 10 minutes, it's sunny and 83 in Boise today), then ran it at 4,000 RPM with the AC on for 5 minutes. No stumble, no sputters, did not die. Took it for a short drive (again with the AC ON) and did my best to put it under load, up and down hills and highway speeds. Again, no issues.

Once I get a good quality regulator and a gauge set up I'll return it to daily driver use and let you know how it goes. Thanks for all the feedback, I was leaning towards a fuel delivery issue, but wouldn't have thought the brand new regulator would fail after only a month! I'll never buy another "Spectre" product if I can help it!

Ok, off to order a good quality regulator, gauge, some fittings and braided steel line

Take it easy,

M_M

[Petros]

It sounds like you fond the problem.

Many times parts are junk right out of the box. I try and avoid buying "commie" made (i.e. made in china) replacement parts, they are just not reliable, especially things like thermostats, water pumps, hoses, belts, etc. All junk as far as I am concerned. Not worth the few $ in savings for the hassle or secondary damage they can cause.

Good luck.

[ARCHINSTL]

Again, I echo splatterdog's comments on Weber install; look at his clean install in his "Weberiffic" thread. See my pix in this thread: http://www.tercel4wd.com/forums/viewtop ... ber#p33319
I got my regulator and gauge through Advance. I'm not at home right now, but it seems that the instructions from Redline said something about max 3psi or so.
Tom M.