Fuel pump circuit cutting out on start up

[Michael Oritt]

My wife's 3000 died over the weekend. On initial investigation it cranked fine and had a spark but empty fuel bowls.

When I turned on the ignition I did not hear any ticking from the SU (her car came with one of the double-headed models) so I checked the circuit to it--test meter showed 12 volts. I disconnected the fuel supply line--The pump would give one gasp and emit a short burst of fuel when the ignition switch was turned on and no more. Same thing when I turned the switch off-one click and that was it. I removed the pump and checked it on the bench--same deal.

I went to the NAPA store and bought a FACET pump. Checked it on the bench and it was fine. I wired and plumbed it in and with the ignition switch turned on it clicked away and apparently pushed fuel to the engine. However, whenever I start the engine the fuel pump dies--I can feel it stop clicking at the same time that the green "ignition warning" light goes off--and within a minute or so the engine dies for lack of fuel. I can also see that the fuel is not being pumped into the transparent inline fuel filter.

When I turn the ignition switch off and then back on the fuel pump energizes and keeps on ticking (less intensely once the system is pressurized) but as soon as I push the start button and the engine fires over the fuel pump switches off and does not come on until I turn the ignition off, then on, etc. etc.

Here are some other observations:

1. If I wire the pump directly to the battery there is no problem. The pump runs with the engine off or on. I can see fuel being pumped into the transparent fuel filter. Everything is fine.

2. When I run a test light to the fuel pump power lead it lights when I turn on the ignition switch, blinks or dims a bit during starting (never really goes out), and stays lighted when the engine is running (this with the fuel pump wired directly to the battery as in #1 above.)

3. When I attach a test meter to the fuel pump power lead the voltage is around 12 with the ignition switch on and the engine off. On startup the voltage goes up to 13+ (it's an analog meter and I'm testing on a 50 volt scale so I cannot get precise readings.)

Best I can tell something is kicking the fuel pump off when the engine starts up but I am lost. I have an alternator if that is important. The pump is wired for negative ground.

Any suggestions will be appreciated.

 

[Keoke]

Hi Michael, that is a bit wierd. However, it sounds like a faulty electrical connection in the fuel pump's normal power circuit.Check all the connections and clean those inline in the power circuit.---Fwiw---Keoke--- /ubbthreads/images/graemlins/savewave.gif----Run the lead to the pump directly from the battery and see what happens when Ignition and start switch are energized. Also check Battery under load and the GND connection.Do not trust the fuse box or the fuses in it make sure they are clean and tight.

 

[Michael Oritt]

Keoke--

I ran a heavy (#12) wire from the inboard lower fuse block post (the one from which the fuel pump circuit is energized)to the hot lead on the fuel pump. Same deal--runs fine when the key is turned on but as soon as I push the starter the pump stops pumping and only turning the key off, then back on re-energizes it, etc. etc.

I'm done for today and hope that someone smarter than me can figure this one out.

I'm stumped--Michael Oritt

 

[vette]

Hello Michael, it seems like such a coincidence, but a similiar thing just happened to my S-10 Blazer. My alternator started putting out AC voltage. It fried the computer. You know the alternator is actually a 3-phase power producer that takes the output of the 3-phase windings and by pushing it through diodes at different phase relationships to the 360 cycle actually puts out pulsating DC voltage. If the diodes get fried and still pass current it will come out as AC. If yours is doing that it could be opening up or shorting out a diode or capacitor in the fuel pump. I'm not sure how the new pumps are built. It could be just an instintaneous hit to the components but not frying it altogether. It's just a thought. check your alternator, i think a reasonably good digital AC volt meter will tell you if you are emitting AC voltage. ..... I also think weak connections might be the problem. Check/replace the fuses, and check tightness of fuse holders, etc. (I guess you don't need to check the fuses since the fuel pump is apparently and unfused circuit. , i should have checked the circuit before i said that. But do check all connections. ) [Why would they design an UNFUSED circuit.]

 

[GregW]

Scratches head…I wonder if something in the overdrive circuit is causing your problem. That’s the only other white wire attached to that terminal on the fuse block, other than the feed from the ignition switch (which seems to be working). Maybe try hooking the pump back up the original way and disconnect the overdrive wire from the fuse block. Don’t know if that will work, but it’s easy.

 

[Michael Oritt]

[ QUOTE ]
Scratches head…I wonder if something in the overdrive circuit is causing your problem.

[/ QUOTE ]

Greg--

No overdrive--Smitty's five-speed.

 

[Jeff_Napoleoni]

This is a fairly simple circuit. I assume that the pump is not blowing a fuse. The first thing I would check is voltage drop to ground. Simply reverse your test leads from B+ to the ground. If you have as little as 2VDC difference, the pump may not work.

 

[Michael Oritt]

I'm embarrassed to continue to take up everyone's time with this problem. However since I've gotten so many helpful suggestions, both on and off list, I feel I owe an update.

(Note: Because the original white wire running under the car and back to the fuel pump is suspect I used a jumper from the switched #3 lead on the fuse block [that's the lower inboard lead] from which the white wires are fed to power the fuel pump and run load tests.)

To summarize the situation:

1. When I turn the ignition key on the (NAPA) fuel pump energizes and pumps fuel till the bowls are apparently full, then goes into it's "idling mode", clicking less frequently and more faintly (much like and SU only a bit louder).

2. As soon as I start the engine the fuel pump stops clicking and pumping, and within a minute the engine dies.

3. If I shut the key switch off and then turn it on again, the same process begins: The pump energizes, etc., only to shut off again on restart.

4. When I clip the jumper running to the fuel pump onto either the battery or the unswitched lead (#1) at the fuse block the pump starts to pump, AND CONTINUES TO PUMP EVEN AFTER THE ENGINE STARTS! No pump shutdown, no running out of fuel, no problem.

Several folks suggested that the problem might be in the alternator and told me to disconnect it and see what happens. With the pump energized off the switched terminal I completely disconnected all wires to the alternator and started the engine with the same result: The pump stops and the engine eventually runs out of fuel and dies. Absolutely no effect on steps 1-4 whether or not the alternator is hooked up.

But here's something interesting: In doing voltage tests at the #3 post and the battery I found that there is about 12.5 volts before starting, that the voltage drops to perhaps 10.5 during cranking and that as soon as the engine fires over the voltage climbs to about 18 volts. That's too high and I am taking the alternator to the repair shop tomorrow. It doesn't explain the problem to me but it is something that I need to put right before continuing.

I have not yet investigated the quality of connections at the key switch which feeds the switched side of the fuse block, though why the heater fan and turn signals on the fused side of that switched circuit continue to work while the fuel pump drops out is baffling.
But perhaps I'll find something there--tomorrow.

Thanks everyone for your patience.

 

[Michael Oritt]

At the end of yesterday's exciting episode I had discovered that the alternator was putting out something like 18 volts or more, so this morning I went to the NAPA store and got a free replacement and installed it.

Before reattaching the alternator wiring I decided to recheck whether or not the fuel pump would drop out when hooked up to the original (still suspect) white power lead WITHOUT the alternator connected to the system--the fuel pump started ticking when I turned on the igntion key and upon starting the engine it continued to run for approximately five minutes. That told me
something--though exactly what I was not sure of.

I then wired the alternator in, went through the same process--this time with an analog voltmeter attached to the battery posts. After the engine started up the fuel pump continued to run normally for about 30-45 seconds, then
dropped out just about the time when the battery voltage went up to peak voltage (about 14.5 volts). That also told me something.

I bought a small 12 volt relay and using the (now not-so-suspect) original white fuel pump power lead I wired the relay to make (close) the circuit so that it would energize when I turned on the ignition key, then ran a #12 wire from
the positive battery post, through the relay's circuit and to the positive lead to the fuel pump. I turned on the key and the fuel pump started to click away. I started the engine and the fuel pump continued to run merrily along. I
went for a five-minute ride and the fuel pump operated perfectly.

It seems to me that there is something in the fuel pump's circuitry that does not like receiving power from the fuse panel when the alternator is running or producing peak power, something that is "cured" when the pump is powered
directly from the battery. Again I am thinking that the battery in some way serves as a filter or buffer, perhaps levelling out some transcients, etc. that are coming from the alternator.

I don't think I have solved the problem so much as come up with a work-around. I'd feel a lot better if I understood the cause and will appreciate any suggestions others might provide.

Thanks everyone for their patience and input.

 

[Keoke]

HI Michael, Glad you set up a workable system. I Thought the pump should run when connected directly off the battery. If that Pump is solid state and the Alternator is dirty,Feeding Back transients on the power lines, It just may effect the pump or that particular pump is overly sensitive. Installation of an inline noise filter at the pump might be a solution,However, It would take a scope to resolve this issue. Here is a thought if you care to play around a bit. May not work{not enough electrical noise} but its an easy try. Connect the Pump to the Horn circuit then blow the horns and see if it quits. Yes the Battery is a big sump for electrical noise, it looks like a large capacitor electrically.---Fwiw---Keoke

 

[Michael Oritt]

[ QUOTE ]
Here is a thought if you care to play around a bit. May not work{not enough electrical noise} but its an easy try. Connect the Pump to the Horn circuit then blow the horns and see if it quits. Yes the Battery is a big sump for electrical noise, it looks like a large capacitor electrically.---Fwiw---Keoke

[/ QUOTE ]

Keoke--

I have $35.00 invested in the pump and frankly am tired of screwing around with it. Allen Hendrix (Hendrix Wire Wheels) tells me that he has been using a "Masters E2019 pump (sold by Autozone) in Healeys that come into his shop with bad SU's for many years with no problems, so I am picking one up tomorrow and will wire it up with the original white wire. I'll see where that brings me.

 

[vette]

Michael, you,ve made some changes and they have all produced the same problem a shutting off fuel pump. Even though i suspected the alternator, I don't believe the second alternator is also bad. Typical story right. If the alternator was bad, why did the pump continue to operate when you powered it off the #1 terminal at the fuse block. The only component you have not investigated is the ignition switch. A bad contact in the switch or a bad terminal connection at the switch could have carried load because you had it at rest for a day, (yesterday you were trying alot of stuff thereby loading and heating the weak joint) then upon use today, the higher voltage (14.5) broke it down. Your relay, even though using the switch, may have been signifigantly less load than the pump. And the pump runs well, you proved that on your 5-minute drive. I'd buy an ignition switch before I would buy a fuel pump.
/ubbthreads/images/graemlins/cheers.gif Dave C.

 

[Michael Oritt]

[ QUOTE ]
The only component you have not investigated is the ignition switch. A bad contact in the switch or a bad terminal connection at the switch could have carried load because you had it at rest for a day, (yesterday you were trying alot of stuff thereby loading and heating the weak joint) then upon use today, the higher voltage (14.5) broke it down. Your relay, even though using the switch, may have been signifigantly less load than the pump. And the pump runs well, you proved that on your 5-minute drive. I'd buy an ignition switch before I would buy a fuel pump.
/ubbthreads/images/graemlins/cheers.gif Dave C.

[/ QUOTE ]

Dave--

Actually I did check it--this morning--by jumping a wire from the unswitched post at the fuse block to the switched post--and got the same results.

I agree that the relay may draw less current than the pump and that there may still be a supply problem but I already special-ordered the pump this afternoon--am picking it up tomorrow.... If it does not work then I will have to go back to square one, probably starting at the wires to and from the keyswitch. Wish me luck! :->

 

[Ed_K]

Since you have experienced these same symptoms with two different fuel pumps, I suspect that a third fuel pump may not help. If problem is still there after you install the autozone pump...
1..When you ran the 12 gauge wire from the fuse block directly to the fuel pump, did you disconnect the original white wire from both the fuel pump AND the fuse block ? If not, try your 12 gauge wire again with both ends of the original wire disconnected.
2..If you did disconnect both ends of the original wire when you ran the 12 gauge bypass wire, then the only thing left is electrical noise from the alternator. I think autoparts stores still sell noise surpression capacitors to eliminate radio noise. Try installing one of these on the output wire of the alternator to ground.
.... Hopefully the autozone pump fixed your problem and you don't need to mess with it anymore.

 

[vette]

Michael, At the risk of becoming a real bore, I'm going to have a go at this one more time. When you powered the pump off of #1 terminal of the fuse block, direct with a new wire, it worked. When you supplied the original wire at terminal #3 with power from #1 terminal it didn't work. Hmm, both terminal 1&3 get power from the "B" terminal of the voltage regulator. I still believe it is a bad connection, contact or wire. Before you install the new pump, just run a new wire from terminal 3 to the pump. Also, did you look really close at the terminal connections of the wires, especially at the fuse block. Sometimes those original wire terminations work loose or corrode and make a bad joint. About a year ago I had to run a new wire for the flasher relay in a BN7 car because the one in the harnest just failed.
Good luck. Dave C.

 

[Healey 100]

This is an interesting problem and shows some of the subtle issues that can be created when original equipment is replaced. I am sure Michael will get to the bottom of it, there is a strange interplay between the alternator and the solid state fuel pump. Perhaps there is some sort of high frequency noise that bothers that fuel pump. Putting a radio suppression capacitor between the fuel pump and ground may clear it up, but who knows.

The Healey was not exactly a highly engineered car, but most of the original electrical systems were simple and did work reasonably well together. Personally, I never understood all the Lucas jokes, I have had very little trouble with the Lucas equipment on my Healey. My generator lost a bearing once. That problem was easily fixed and otherwise it seems fairly bullet proof.

So why switch to an alternator? I suppose because the original generators are now hard to find?

Good luck!

 

[Keoke]

[ QUOTE ]


So why switch to an alternator? I suppose because the original generators are now hard to find?

Good luck!

[/ QUOTE ]


No Healey 100,There are virtually all the parts available to rebuild a generator as new. However, this can be quite costly. The generator has a limited output and fails to charge at idle. When additional High current loads,Special High current lamps, High current sound systems etc, are installed in the cars the generator simply will not keep the battery charged. Additionally, the alternator is reportedly a more efficient and reliable device than the Dynamo!. On the otherhand, if the car is kept in its original configuration and you do not travel long distances at night,the generator although marginal probably will not cause one any serious problems---Fwiw---Keoke

 

[dklawson]

I've followed this thread for a while w/o contributing as so much of it is focused on very specific aspects unique to Healeys. Since so much of British wiring is common between the different marques I do think there are a couple of things you might want to try since originality doesn't appear to be your main focus at this point.

You know the pump works when wired directly to the battery. According to your tests, the pump works this way regardless of what's going on with the charging system. You know therefore that you have a fundamental problem with the power wiring to the pump. God knows what. I do not believe your problem is in any way related to the charging system as any "noise" introduced by the charging system would still be present when you wire the pump directly to the battery.

You also know that your ignition coil is working. You should be able to pull a NEW white wire from the ignition switch side of the coil to the fuel pump. This will give you switched power for the pump. If you're worried about current draw on the single wire between the switch and coil, use a relay in the circuit (like when you add auxiliary lights). If you do this and the pump has a good ground wire connection it should work without issue.

I agree with Keoke's comments about the alternator. In general, the alternators are more reliable than the generator and its control box. The issue becomes a trade off between reliability and originality.

 

[Healey 100]

Our Healey has been driven to most of the Healey events in the west, usually involving thousands of miles over the road. We often use the car at night. I just have never had any sort of problem maintaining a charge on the battery. Sure, it leaks oil and the rain comes right in -- but poor generator performance is pretty low on my list of shortcomings with the car.

We don't have a lot of accessories in the car, but modern radios, unless you have some sort of monster boom amp draw very little power.

Just my 2 cents. Now on our next trip my the generator will fail and I'll eat crow on the side of the road....

 

[Ed_K]

At the risk of adding too much information, I asked if he had disconnected the original wire at both ends before he installed the bypass 12 gauge wire for the following reason; If he left either end of the original white wire connected to either the fuel pump or the fuse block and the original white wire was damaged like my original white wire that I just replaced a couple of weeks ago, the original white wire may be shorting to ground under the " right " conditions. My car's fuel pump was working OK when I start the car in the garage or driveway for 5 minutes, ( car has not been driven on the road since 1979 ), but I found the white wire had at one time gotten so hot that it had melted all of the insulation off of the white wire for 2 feet where the cable takes a 90 degree turn to run along the frame near the front corner of the transmission tunnel. If I had not found this when I still had the transmission tunnel cover off of the car, I would have completed the restoration and started to drive it and as soon as I had the " right " conditions, my fuel pump would most certainly have stopped working. I also added an inline 15 amp minfuse in the engine bay right before the white wire goes down through the gromet to keep it from happening again. I also added another mini fuse for the red wire going to the tail lights. The white wire had gotten hot enough that it also melted away a little bit of the red wire's insulation right at the 90 degree turn where the white and red wires turn twards the back of the car under the front left side of the trasmission tunnel cover.