| Dream38v8 | -- 04-05-2026 @ 5:46 AM |
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As in a previous thread my '38 was running great with all its new equipment. As I was returning from Cars and Coffee yesterday the car suddenly lost power. The car won't go above 20mph. I noticed the amp meter wasn't charging or discharging. Once home I connected the charger to the battery. It read 6.1V. Turning the fog lights on also didn't affect the amp meter reading. Is the issue the generator or cutout or both? Thank you in advance. I had big dreams of finally being able to drive the '38 of Drive your V8 Day. I still hope I can. Ray
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| carcrazy | -- 04-05-2026 @ 8:46 AM |
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If your car loses power and won't drive over 20 MPH, there are a few things to check first. Check to see if you engine is getting adequate fuel. Sometimes an engine will get enough fuel to idle but not enough to run at speed while pulling a load. Your fuel pump may be failing or your fuel line may be partially blocked or have some leaks. Your exhaust system or muffler(s) may be partially plugged. The vent to your gas tank may be plugged causing a vacuum in you fuel tank. Your air cleaner may be plugged or the choke plate in your carburetor may be closed. Your ignition coil may be failing. Hopefully you will be able to find and correct the problem. What was the outside temperature while you were experiencing this problem. Your car could be experiencing vapor lock.
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| MG | -- 04-05-2026 @ 11:50 AM |
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One barrel/one side of your carburetor clogged thus causing the engine to run on just 4 cylinders...
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| Dream38v8 | -- 04-05-2026 @ 12:31 PM |
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Carcrazy and MG, thank you for all your suggestions. 1) Butter fly is wide open (carb new < 100 miles) 2) Ran the same with air cleaner completely off 3) removed gas cap 4) Checked flexible fuel line with engine running (no issue and a new fuel line installed < 100 miles) 5) Ran car with electric fuel pump operating during this check (new < 100 miles) 6) Exhaust equally strong from both pipes (running Fenton headers) Since both exhausts are strong both carb barrels are working 7) Outside temp was approx 75 and engine temp <160deg How do I test the coil output? Did all the above with a battery charger conncecting. Thanks again! Ray
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| carcrazy | -- 04-05-2026 @ 2:08 PM |
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One quick and dirty way to check coil output, is to pull one of the spark plug wires from a plug and hold it next to a cylinder head nut or other non-painted part of the engine to check the spark. The spark should ideally be blue and able to jump a 1/4" gap. Are you using the original equipment type of spark plug wires which feature solid metal wire cores? These are the best. If you have radio resistance or other carbon core wires, be aware that these are known to fail after many heat cycles or miles.
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| carcrazy | -- 04-05-2026 @ 11:38 PM |
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One of the vacuum lines on the engine intake manifold may have come off allowing a massive vacuum leak. Your vacuum windshield wiper motor may have developed a leak. Try running the engine with all of the vacuum tubes plugged with caps.
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| Dream38v8 | -- 04-06-2026 @ 5:27 PM |
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Carcrazy, just saw your note regarding vacuum lines. As for the coil test checking spark plug spark. The spark is very strong and blue at the tips, but white in the middle. Should the entire spark be blue? Thanks, Ray Ray
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| carcrazy | -- 04-06-2026 @ 5:53 PM |
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Your spark sounds great. Your coil is probably OK. Sometimes coils breakdown as they heat up. Is your spark still this good after the coil is hot and after the car has been drive several miles?
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| Dream38v8 | -- 04-07-2026 @ 5:09 AM |
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Carcrazy, I'll be checking the vacuum lines later today. FYI when the car lost power the engine temp was under 160 and outside temp was in the mid 70s. The amp gauge was neutral prior to losing power. When I turned on the headlights and fog lights the gauge did not discharge. Ray
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| carcrazy | -- 04-07-2026 @ 9:47 AM |
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Ray, The fuel level in your carburetor may be too low starving the engine of fuel at speeds above idle. There may be some blockages or air leaks within your carburetor preventing the main system from flowing the proper amount of fuel.
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| TomO | -- 04-09-2026 @ 10:57 AM |
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Your spark seems fine, now you need to find out if the fuel line or pickup is plugged by checking fuel delivery. To check fuel delivery, you need a graduated 16 ounce or larger container to determine the amount of fuel delivered in a measured time. Disconnect the fuel pump line from the carburetor and direct it into a graduated container. Crank the engine long enough to get 2 ounces of gas in the container and then continue cranking for 15 more strokes of the pump. The pump should have delivered 6 more ounces of gas. If you have sufficient fuel, the next step is to check your compression and spark plug condition. Tom
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| Dream38v8 | -- 04-11-2026 @ 11:02 AM |
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Carcrazy and Tom, here is what I have done since your last notes: - checked sparkplugs, cleaned and gapped / one plug was gapped .028 while all the others were @ .025. The car ran the same before and after cleaning the plugs - disconnected the wiper vacuum line / car ran the same when I plug the vacuum intake (wipers), but died when I unplugged the vacuum intake. I'm still wondering if this is a electrical issue as the amp gauge stays neutral with all lights on. The gauge never shows a charge or discharge. Tom, I haven't had an opportunity check the fuel delivery. Ray
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| TomO | -- 04-13-2026 @ 9:29 AM |
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The amp gauge shows the current flowing in the battery circuit of the car. The wire comes from the battery side of the starter solenoid through the ammeter loop to the fuse block. If the ammeter is not responding and the wire is going through the loop, it is most likely that the ammeter is bad. As far as the engine is concerned, the electrical issue that would affect performance is a weak spark. Your post claims a strong spark. The engine needs adequate fuel, good air flow, good compression and good spark to produce power. You have checked the spark, checked the plugs, but did not check compression and fuel delivery. Another check is to connect a vacuum gauge in place of the wiper connection and view the vacuum the engine is producing at idle and higher steady rpms. Van pelts sales has a good vacuum chart. http://www.vanpeltsales.com/FH_web/FH_images/FH_other-pics/vacuumgauge-chart.jpg Tom
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| carcrazy | -- 04-16-2026 @ 2:47 PM |
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Dream38v8, Have you checked inside the carburetor for any loose screws which would allow vacuum signals to be reduced so the main fuel system is not flowing adequate fuel? Have you checked the cylinder compression so that each cylinder has enough to provide adequate power? Should be about 100 PSI or more. What is the altitude where you are experiencing power loss? Is the carburetor bolted tightly to the intake manifold with a good gasket to provide an air-tight seal? What is your idling manifold vacuum? Check with a vacuum gauge, should be about 19 in. hg. at sea level altitude. Please let us know what you find.
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| Dream38v8 | -- 05-07-2026 @ 6:06 AM |
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I haven't had the opportunity to work on the '38 in the last month. I hope to get to checking the fuel flow today. BTW I noticed the new fuel pump has a glass bowl white the original did not. Is there any issue using the glass bowl fuel pump. Thanks Ray
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| carcrazy | -- 05-07-2026 @ 7:18 AM |
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If the glass bowl fuel pump bolts onto the engine without interfering with anything else on the intake manifold, it is OK to use. The fuel pumps without the glass bowl are getting harder to find so you will see many of the older Fords with the glass bowl fuel pumps now.
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| TomO | -- 05-08-2026 @ 9:17 AM |
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Another issue with the glass bowl fuel pumps is if you put the car in Concourse judging you will lose a few points. They make it easier to see if debris is coming from the tank or lines. Do not overtighten the thumb screw holing the glass bowl in place, you could warp the housing causing poor fuel pump priming. Did your ammeter start working again? Tom This message was edited by TomO on 5-8-26 @ 9:20 AM
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| Dream38v8 | -- 05-10-2026 @ 1:02 PM |
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Carcrazy and Tom, thanks for the info on the glass bowl. There is no plans to enter any judging contest. The car is really clean, but not show quality. Life keeps getting in the way of working on the car. I did note the glass bowl is full with no debris (clear). I really appreciate your advice. Ray
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| ford38v8 | -- 05-10-2026 @ 4:25 PM |
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Ray, one confirmation of previous info: you tested spark at the plugs as good strong blue spark, but was that test done immediately after your engine stalled, or while no problem existed? An ignition coil may perform differently at different temperatures, and not necessarily only at extreme temperatures. The only spark test that can accurately diagnose a bad coil is at the time the engine stalls. Alan
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| Dream38v8 | -- 05-18-2026 @ 10:28 AM |
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Tom, I finally found time to work on the '38. The fuel bowl is clear / clean. I removed the fuel bowl to check its filter / screen. I found a small piece of clear film / slime on the filter. It covered less than 1/100 of the screen. I am now ready to check the fuel flow / delivery. In this note you mentioned 15 strokes of the fuel pump. I do I determine 15 strokes? Is there an audible sound from the pump? How long should the pump take to deliver 6 oz. in 15 strokes? Thanks Ray
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| Dream38v8 | -- 05-18-2026 @ 11:24 AM |
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Tom, as you can probably surmise you are working with a V8 novice. I understand a fuel pump stroke now after repeating the 15 stroke procedure multiple times. We did the procedure multiple times. Each time approx. 4oz of fuel was delivered between 22 and 24 seconds. If I extrapolate out to 6 oz it would take approx. 22 strokes and 33+ seconds. Thanks again! Ray
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| Dream38v8 | -- 05-19-2026 @ 4:57 PM |
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So my fuel pump is not producing the necessary quantity of fuel to the carb. Correct? Ray
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| TomO | -- 05-21-2026 @ 3:18 PM |
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Ray, I am sorry about the delay in replying to you. I just did not see your post. A fuel pump stroke is when the fuel spurts out the line. Because your fuel starvation started suddenly, I suspect a clogged fuel line or tank pickup. Disconnect the fuel line at the tank and at the fuel pump. Direct the tank end of the line into a container so you can see what comes out of the line. Use compressed air to blow from the firewall end to clear the line. Then blow into the tank connector to clear the pickup. If you do not have an air compressor, you can use a can of air, like the ones used to clean keyboards. If you use the canned air, make sure that you disconnect the electric fuel pump from the line. The canned air is not strong enough to blow backwards though some of the electric fuel pumps. I just read where you said there was a small piece of clear film on the screen of the glass bowl. Some gas tank sealers break down when the come in contact with Ethanol. You can inspect the interior of your tank by removing the sending unit. There should be a small opening in your trunk floor t you can use to access the sending unit. Use a mirror to inspect the top of the tank. It should be steel colored or surface rust colored. Any other color means that it was coated. You will not be able to see the complete tank top or bottom, but if you empty the tank, you should be able to see the pickup area. That is where you would seedamge to the coating. Tom This message was edited by TomO on 5-21-26 @ 3:20 PM
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| Drbrown | -- 05-23-2026 @ 7:52 AM |
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Using a meter, one can check the fuel flow pressure on the output side of the pump. My vacumm meter does both vacumm and gas pressure readings. I believe Pump output pressure should range from about 1-1/2 minimum to 2-1/2 lbs maximun. Obviously if below minimum something is wrong.
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| carcrazy | -- 05-23-2026 @ 9:07 PM |
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Suspect a small leak in the fuel line somewhere between the tank and the mechanical fuel pump on the engine. This leak will allow air to bleed into the fuel when you use only the mechanical pump which uses vacuum to provide fuel flow. When you use the electrical pump, the pressure in the fuel line will provide the amount of fuel required for the engine to run normally.
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| Dream38v8 | -- 05-31-2026 @ 12:18 PM |
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Well I told life it had to wait as I wanted to get back to solving the '38 power loss issue. After removing the trunk shelf I had clean access to the fuel tank sender cover. I removed the cover and the fuel tank sender unit with floats. From what I could see the tank is clear. The side walls and tank floor were gray and rust colored. No other color was present. The sending unit cork floats were clean. There was no residue on the floats. As this unit stopped working years ago I will replace it. From what I read on this Forum new units are not much better. The fuel pump glass bowl has remained full during the power loss issue with no visible air bubbles. New items that were installed this Spring: electric fuel pump and filter, input flexible gas line to the fuel pump, fuel pump, new copper line to the carb and a new carb. I was hoping to be able to drive my V8 this year on "Drive your V8 Day". Is there hope? Thanks! Ray
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