72 Series 3 stalling under load - SOLVED!

[sdebruler]

Hello Everyone I got a problem that has me stumped. Hopefully the collective knowledge here can help sort me out!

Darla - My 1972 Series 3 2.25 Petro engine

Started about a month ago....

While under load (climbing a hill or on the highway) I begin to lose power and have actually stalled a few times.

If I'm on the highway doing approx 50mph I can curise along just fine until I come to any sort of hill to climb. On the hill Darla will begin to rock back and firth (sometimes violently) and begin to lose power. I have to decelerate and hope up to get to the top of the hill before it stalls. Yikes!

Starts and idles fine both cold and hot. I can cruise around town with almost no problems.

Since the problem started I have done the following:

Rebuilt the carb (Zenith)
Drained the fuel tank
Blew down the fuel lines
Cleaned the fuel pump bowl
Replaced the fuel filter
Rebuilt the fuel pump (didn't need to)
Checked timing (good with 6 degrees advance) @approx 950rpm

Back in May approx 2000 miles ago
Full tune up including plugs, timing adjustment, compression check, fluids, filters, ext...


I'm feeling like this might be related to the distributor, but I just don't know. Back in 2014 I rebuilt the distributor added electronic ignition, new coil and plug wires.

Any help would be appreciated.

[erik88lr]

Had a similar problem, hooked up a fuel pressure gauge and found pressure to the carb dropped to zero under high load. Went through several replacement pumps that worked just as poorly before finally installing an electric pump. Problem solved. Your mileage may vary.

[michelle]

A coil with carbon tracks or bad plug wires will also cause an engine to miss fire under a load.
Watch the engine under load (put some wheel chocks under the tires, get someone to stand on the brakes with the transbrake applied and feather the clutch) in a dark garage.
IF you have any carbon tracking on your coil or leaky spark plug wires, you should see it sparking at the coil top, or where your wires touch any metal. Be sure to check for carbon tracks inside your distributor cap as well. Sadly, now that parts suppliers take the lowest bidder to make their wares, a part being new isnt a guarantee that a part is good!

If you put your rover under load this way be careful to make sure you dont burn up your clutch, your car is pointing out of the garage and there are no vehicles you havent insured excessively in the line of sight!

[01birddog]

My Series III did almost the same thing as yours to include the "sometimes violently" part. I ask questions here and related to what i had done to try and fix it. I was sure it was a fuel issue and went in that direction with no success. Finally changed the new distributor to try a trashy,filthy one i had in a Series II and problem fixed. I am rebuilding a good, original Lucas now to drop in.

[sdebruler]

erik88lr, michelle & 01birddog,
Thank you for the replies. This weekend I plan to inspect the ignition system closer, but my job my have other ideas for me and I my have to travel instead... Yuck!

Here's what i have on my list of things to inspect.

Visual inspection of the ignition system
Check all connection
Open distributor cap and check for carbon tracks - Thanks Michelle
Pull spark plugs and check gap
Pressure test vacuum advance - Not sure what the what pressure to hold. Thinking 30psi for 30 seconds?
Preform Resistance measurement of the ignition coil

If nothing comes of those inspections I'll start with replacing the distributor - Thanks 01birddog

erik88lr - Which electric fuel pump did you use?

[erik88lr]

erik88lr, michelle & 01birddog,
Thank you for the replies.....

If nothing comes of those inspections I'll start with replacing the distributor - Thanks 01birddog

erik88lr - Which electric fuel pump did you use?

This is the pump I got a couple of years ago: https://www.amazon.com/gp/product/B000BZX92K/ref=ppx_yo_dt_b_asin_title_o09__o00_s00?ie=UTF8&psc=1 I mounted the pump under the passenger seat access panel, on the frame above the fuel tank, plumbed to pump fuel in parallel to the mechanical pump, as plumbing it in series caused problem. (Mechanical pump had problem pulling fuel through the electric pump, aggravating the power loss problem when not using the electric pump.)

No offense, but I'd encourage you to do what diagnosis you can, prior to replacing parts. O'Reilly autoparts had a small low pressure fuel gauge that I could plumb in at the carb inlet and read from the driver's seat. That showed the fuel pressure drop under load. If you do replace any parts be sure to do so one at a time and then test drive the truck, or else you won't know what part fixed the problem.
Here's a thread on my similar problem: http://forums.roversnorth.com/showthread.php?16844-Series-III-surging

Cheers,
~erik~

[sdebruler]

Erik,
Thanks again! I will continue to diagnose prior to any part replacement and report back here to bookend the thread. I have an old (original) used and maybe good fuel pump. Will install that and see if the conditions change.

BTW, that pump you recommended is no longer available are is there a recommended GPM or PSI I should be looking for in an electric fuel pump? If i end up going with a electric pump i will do as you recommend run in in parallel with the existing pump.

[fly cubs]

Erik,
Thanks again! I will continue to diagnose prior to any part replacement and report back here to bookend the thread. I have an old (original) used and maybe good fuel pump. Will install that and see if the conditions change.

BTW, that pump you recommended is no longer available are is there a recommended GPM or PSI I should be looking for in an electric fuel pump? If i end up going with a electric pump i will do as you recommend run in in parallel with the existing pump.


I had the same stalling issue a few years back. I swapped the distributor to a brand new Pertronix D176600 that was a copy of the Lucas 45d, installed a new Pertronix coil, quality wires and a new set of plugs. What a difference, especially when things got hot. No skipping under load, just smooth power.

I also switched last summer to the TDI mechanical pump- fits right on a 2.25 petrol, although the inlet and outlet are reversed- hoses still fit. This made a significant difference in reliability and vapor lock. I called our hosts, and they knew exactly what I was looking for when I asked. While I see why some folks might go the electrical pump route, I'm just not a fan of adding complexity to one of the simplest machines I own.

[erik88lr]

Erik,

BTW, that pump you recommended is no longer available are is there a recommended GPM or PSI I should be looking for in an electric fuel pump? If i end up going with a electric pump i will do as you recommend run in in parallel with the existing pump.

I think any electric pump made for carburetted engines should work. If it'll supply enough fuel for an old American V8 it should do so for our little four bangers. Just don't get a high pressure pump made for fuel injected engines! This is the fuel pressure gauge I Tee'd into the fuel line to the carb: https://www.amazon.com/Mr-Gasket-1561-Pressure-Gauge-x/dp/B000BWCFLO

Pressure, as I recall, was in the three to five psi range when all was well. When the carb ran out of fuel due to the pumps inability to deliver a sufficient quantity the pressure dropped to zero.

I went through three or four new mechanical pumps as well as rebuilding my original pump. All were inadequate, but with no blockages in the system it just had to be the pump. I thought the cam might have worn such that the pump stroke had decreased, but that wasn't the case. I suspect that if I had a stronger spring above the pump diaphragm the pressure/volume would increase but the electric pump made that unnecessary. The other nice thing about a switched electric pump is that I can use it to fill the carb up and speed starting after the trucks been sitting for several weeks.

[sdebruler]

Problem solved!

Added an electric fuel pump inline with the mechanical pump. 3-7 psi pump / 12vdc. Thanks to Erik for the advice.

[erik88lr]

Problem solved!

Added an electric fuel pump inline with the mechanical pump. 3-7 psi pump / 12vdc. Thanks to Erik for the advice.

Glad it worked for you!

You might want to rethink the fuel line routing though. If it's literally inline then there is the potential of a torn mechanical pump diaphragm in the future allowing the electric pump to pump fuel into the crankcase. Also you may find, like I did, that the mechanical pump has trouble pulling fuel through the electric one, so the power loss problem is worse unless the electric pump is switched on.

I ran my hoses in parallel, so I can run the engine on only the mechanical pump except when the electric one is needed to fill an empty carb or deal with vapor lock or high load. The plumbing is a bit more complicated, but not too bad. Just requires more hose and some tee-fittings.

Other options would be to bypass the mechanical pump so it's in place but no fuel goes in or out of it, or to remove it entirely and install a blanking plate.

[cedryck]

Problem solved!

Added an electric fuel pump inline with the mechanical pump. 3-7 psi pump / 12vdc. Thanks to Erik for the advice.
Can someone speak more about the TDI fuel pump fix for series awful mechanincal pumps a part number would be great, thanks, cheers.

[fly cubs]

Can someone speak more about the TDI fuel pump fix for series awful mechanincal pumps a part number would be great, thanks, cheers.


Cedrick - Part number at Rovers North is: PLF299. Bolts right on, just note that the connection closest to firewall is the outlet. My factory hoses still reached. I added a filter between the tank and the pump as well. I'd say my instances of vaporlock were down by half- this summer I'm going to insulate the hose going from the pump to the carb and see if that eliminates it.

https://www.roversnorth.com/ProductDesc.aspx?code=PLF299