Bad MAF symptoms

[General karthief]

Have you changed the filter yet?
I'd do that first and see if the pressure stabilized but in reality it's likely the pump, some don't last that long with todays fuel.
They make a low pressure in tank fuel pump that's better than the in line pumps.

 

[stanggt95]

Have you changed the filter yet?
I'd do that first and see if the pressure stabilized but in reality it's likely the pump, some don't last that long with todays fuel.
They make a low pressure in tank fuel pump that's better than the in line pumps.

No, I haven't done anything yet. I've order some suspension parts and some gaskets. I wanted to try and pinpoint the motor problems before I just start throwing parts at it. The previous owner (not the one who did the motor work) used regular 87 gas in it). I've been using 90 octane ethanol free. Seems to run better on that. Still only getting approximately 13 mpg

 

[General karthief]

Ok, here is what I would do:
Get those plug wires straightened up, if they are questionable replace them, make them hang in the right places and not touch.
Change the plugs, gap them for a carb setup with electronic ignition (.35?) Use copper plugs, nothing special.
Check timing, start at 10* btdc you can bump it up later when you get it running good.
Change fuel filter, if your pressure is still suspect replace the pump, make sure you get one for a carb, remember 7psi max. Nothing special.
Make sure cap and rotor are good.

 

[7991LXnSHO]

@General karthief .35” is a very big gap. I don’t think even a smog era HEI spark plug is supposed to be gapped without a zero after the decimal point. ;-)

 

[stanggt95]

View: https://youtu.be/EXZ9UQNk_SY

 

[General karthief]

@General karthief .35” is a very big gap. I don’t think even a smog era HEI spark plug is supposed to be gapped without a zero after the decimal point. ;-)

I knew that, just testing.
Ahhh, you passed.
Anybody else catch that?

 

[tmoss]

Looks like your regulator has a recessed allen in the center of an external jam nut. DId you loosen the jam nut before trying to adjust the pressure with the allen?

 

[stanggt95]

So here is where I'm at. I've replaced the fuel pump with a more basic pump. A holly low pressure 4-7 psi pump. The one that was on there was way more than the car really needs. Then I removed the canister fuel filter and the fuel pressure regulator and went directly to the carb. It isn't cutting off anymore bit it still has somewhat of a jerky acceleration. I think the fuel pressure gauge is off though because it fluctuates from 0-1.5. The only other things I'm thinking i could change would be to move the fuel filter to the fuel line coming off the gas tank. Also remove the copper fitting and the pressure gauge. The copper fitting could be causing vapor lock. Also when it was originally converted to an external fuel pump, if they didn't remove the internal pump, the fact the external pump is pulling fuel through the internal pump may be causing fuel delivery problems.

 

[7991LXnSHO]

Fuel pumps are rated for volume and pressure. Those specs will vary with the pump. The manuals for my carbureated cars have them listed. If I am even partway caught up here, electrical and Holley mechanical pumps will have their own listed specs. Take off the carb fuel feed, run a hose to a container and measure how much it flows when you crank it for the specified time.

 

[Dan02gt]

I can’t get past that wiring. Parallel splicers everywhere, even used to extend wires.
If the rest of the carb conversion was done at the same level of workmanship as that, you’re in for a nightmare. I would go back and verify/fix every part of the fuel and ignition system. There’s no telling what you will find.

 

[stanggt95]

I can’t get past that wiring. Parallel splicers everywhere, even used to extend wires.
If the rest of the carb conversion was done at the same level of workmanship as that, you’re in for a nightmare. I would go back and verify/fix every part of the fuel and ignition system. There’s no telling what you will find.

I've bought several things I know right off the bat that it needs. I'm gonna get it over to a buddy of mines shop Monday morning. I'm off work the next couple weeks so I'll actually have time to get into it more in depth.

 

[stanggt95]

I can’t get past that wiring. Parallel splicers everywhere, even used to extend wires.
If the rest of the carb conversion was done at the same level of workmanship as that, you’re in for a nightmare. I would go back and verify/fix every part of the fuel and ignition system. There’s no telling what you will find.

Having it looked in to tomorrow. I've got new wires that we're gonna cut to the proper length and new plugs, just to start. Once we verify everything is dialed in correctly, if its still not running right we'll move on to the distributer, cap/rotor then re time it. Hoping its nothing more serious then that.

 

[stanggt95]

Wiring re done

 

[stanggt95]

Apparently there was a second fuel filter back towards the rear of the car along with a disconnected vaccume line below the distributor. So we're gonna remove the front fuel filter and re connect that vaccume line and see if that makes a difference.

 

[7991LXnSHO]

If you do not know how long the filter has been on the car, I would change it.

 

[stanggt95]

Filter is new... motor seems to be running fine...however when I was taking it from my buddies shop to get an alignment, since we replaced the entire front suspension and rack and pinion it overheated. For some reason the fan isn't coming on. Gonna check into that today. SMH...Hate getting into someone else's project where we have no idea what was done...

 

[stanggt95]

Final result so far. Removed fuel filter from under hood. There is one on the fuel pump. Removed fuel pressure regulator. Rewired everything, re did spark plugs/wires. There was a vaccume line disconnected under the distributor. Fixed that. Replaced steering rack/pinion, tie rods, ball joints, sway bar links, oil pan gasket, and new power steering lines. Drives/rides beautifully and runs A LOT BETTER. Still has this studder sometimes under acceleration. Not sure if it still could be the timing is off, or the carb needs adjusted. Anyone have any ideas?

 

[Dan02gt]

I don’t have any advice to offer in the studder. Carbs really aren’t my thing. I just wanted to say the work you did under the hood looks way better!

 

[General karthief]

I will say, in that last pic showing the pump/filter, is real close to that exhaust pipe, I would move it or at the very least insulate it from the heat that exhaust pipe is going to generate, the low fuel pressure required for carbs are very prone to vapor lock.

 

[stanggt95]

I will say, in that last pic showing the pump/filter, is real close to that exhaust pipe, I would move it or at the very least insulate it from the heat that exhaust pipe is going to generate, the low fuel pressure required for carbs are very prone to vapor lock.

Yeah pretty much anywhere you mount it next to the tank is gonna be pretty close to the exhaust. Really nothing we could do about that.