Fuel Return question

KBabcock

KBabcock

True Classic
Car is not starting and thought it was spark but that all checks out. Now looking at the fuel system and before running through the FI trouble shooting I want to check the fuel pump. Namely want to confirm the fuel pump is working. I have turned on the ignition and push the air meter flat open to turn on the fuel pump. I can hear the electrical spin of the pump but don't hear the fuel returning to the gas tank.

Last year when the tank was 1/2 filled and I was checking the fuel system I could hear the fuel trickling back into the tank like running water. The question I have is would I still hear this running water sound if the gas tank is full?
 
Maybe not? The best way to verify fuel flow is to disconnect the return hose somewhere and stick it in a jar to see the fuel flowing. And then you can attach a pressure gauge to that disconnected hose to check if the flow is within spec.

These Bosch pumps are extremely robust. About the only reason they fail is due to excessive rust debris clogging them up (they have a non-serviceable filter screen internally). However other components in the fuel system could be blocking the fuel flow.

And general fuel flow through the system isn't the only cause of a lack of fuel in the combustion chambers; check that the injectors are getting a electrical signal and opening/closing correctly. It would be unusual for all four injectors to clog, but injectors can get clogged.
 
I could kick my self because when I went through this last year I bought an in line fuel pressure gauge but it was the wrong size connector for the hoses and I never bothered to get the right one, figured I would do it later...Arrrggg. Need to run through the FI procedure again something went south over the winter.
 
KBabcock said:
Car is not starting and thought it was spark but that all checks out. Now looking at the fuel system and before running through the FI trouble shooting I want to check the fuel pump. Namely want to confirm the fuel pump is working. I have turned on the ignition and push the air meter flat open to turn on the fuel pump. I can hear the electrical spin of the pump but don't hear the fuel returning to the gas tank.

Last year when the tank was 1/2 filled and I was checking the fuel system I could hear the fuel trickling back into the tank like running water. The question I have is would I still hear this running water sound if the gas tank is full?
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The FI return is at the bottom of the rank. I am not sure returning fuel would make a running water sound. Maybe it was bubbles from empty lines as the system filled?
 
JimD said:
The FI return is at the bottom of the rank. I am not sure returning fuel would make a running water sound. Maybe it was bubbles from empty lines as the system filled?
Click to expand...
Damn, you're right Jim. That is so odd because I did hear the return noise, maybe the tank was more empty then I thought at the time. I believe the pump is push fuel, I just need to see if it is at the right pressure. I plan to put a permeate pressure gauges the fuel line that runs between the fuel filter and the metal line. Looks like a can fabricate a melt mounting bracket that can bolt on to the engine cover hinge bolts. Just need to get some high pressure fuel line. Looks like the ID should be 7mm. I wonder if a 1/4" line would work?

So odd that last fall it started and ran great now the engine turns fine but can can barely hear it trying to ignite. May suspicion is the FI so, back to running through the trouble shooting guide.
 
KBabcock said:
Damn, you're right Jim. That is so odd because I did hear the return noise, maybe the tank was more empty then I thought at the time. I believe the pump is push fuel, I just need to see if it is at the right pressure. I plan to put a permeate pressure gauges the fuel line that runs between the fuel filter and the metal line. Looks like a can fabricate a melt mounting bracket that can bolt on to the engine cover hinge bolts. Just need to get some high pressure fuel line. Looks like the ID should be 7mm. I wonder if a 1/4" line would work?

So odd that last fall it started and ran great now the engine turns fine but can can barely hear it trying to ignite. May suspicion is the FI so, back to running through the trouble shooting guide.
Click to expand...
FI needs 7.5mm or you can use 8mm. If using 8mm you can’t use the old collars, you will need to use FI type clamps or Oetiker type clamps.

It is best to put the pressure gauge after the filter as you want to measure pressure at the injector rail not the possible restriction in the filter.
 
I dunno....but if you can hear the fuel pump running you likely have fuel pressure......

Perhaps...back to basics.....if you have fuel pressure...are the injectors opening ??

Cheap and easy test to know a bit more...just hook up one of these to see if injectors are indeed getting a signal to open:

www.harborfreight.com

Noid Light and IAC Tester Set 11 Pc

Amazing deals on this Noid Light And Iac Tester Set 11Pc at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com

you can likely find cheaper on amazon or Ebay.......or borrow one from a friend or auto parts loan-a-tool........

Canadian folks might want to grab one of of these while they last:
 
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rx1900 said:
I dunno....but if you can hear the fuel pump running you likely have fuel pressure......

Perhaps...back to basics.....if you have fuel pressure...are the injectors opening ??

Cheap and easy test to know a bit more...just hook up one of these to see if injectors are indeed getting a signal to open:

www.harborfreight.com

Noid Light and IAC Tester Set 11 Pc

Amazing deals on this Noid Light And Iac Tester Set 11Pc at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com

you can likely find cheaper on amazon or Ebay.......or borrow one from a friend or auto parts loan-a-tool........

Canadian folks might want to grab one of of these while they last:
Click to expand...
noid light, not needed often, but when it is there is nothing like it!

Odie
 
KBabcock said:
. I plan to put a permeate pressure gauges the fuel line that runs between the fuel filter and the metal line.
Click to expand...
I installed my gauge on the fuel hose that comes off the rail and goes to the cold start injector. No mount needed, I used a zip tie to the cold start air hose for support. Also 7.5mm hose seems to be hard to find or not very good quality. I used 5/16" hose with fuel injection type hose clamps.
20200823_215557.jpg
 
Again. Kevin.....back to basics...did you splurge for one of these Harbor Freight spark testers and confirm you indeed have a strong regular spark ??

and did you yank off the intake hose at the throttle body....open the throttle...and give it a good squirt of starting fluid:

www.homedepot.com

Gumout 11 oz. Starting Fluid 5072866 - The Home Depot

Engines need the right conditions to perform properly. If temperatures drop too low, gasoline can have problems evaporating, making it harder to burn. Extreme humidity can also have an effect on fuel's
www.homedepot.com

If it fires for a few seconds with that.....go from there......
 
nichol01 said:
I installed my gauge on the fuel hose that comes off the rail and goes to the cold start injector. No mount needed, I used a zip tie to the cold start air hose for support. Also 7.5mm hose seems to be hard to find or not very good quality. I used 5/16" hose with fuel injection type hose clamps.View attachment 75876
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I did think of that and it is a good location, I just wanted to keep the engine as clean as possible for when I need to take things apart. Also a little less heat were I want to put it. Nice set up.
 
rx1900 said:
Again. Kevin.....back to basics...did you splurge for one of these Harbor Freight spark testers and confirm you indeed have a strong regular spark ??

and did you yank off the intake hose at the throttle body....open the throttle...and give it a good squirt of starting fluid:

www.homedepot.com

Gumout 11 oz. Starting Fluid 5072866 - The Home Depot

Engines need the right conditions to perform properly. If temperatures drop too low, gasoline can have problems evaporating, making it harder to burn. Extreme humidity can also have an effect on fuel's
www.homedepot.com

If it fires for a few seconds with that.....go from there......
Click to expand...
I did indeed but having no previous bench mark as to what the light should show for a strong spark. The three file below are videos of 3 of the plugs. The videos are longer then they need to be as the sparking is only a few seconds towards the middle. Let me know what you think if you have used this tester.


Also also did the starter fluid test and did not get the short run which I would expect but seeing the spark in the tester light created a dilemma as to what is wrong. I recently changed ignition wires and plugged back in the old ignition wires with no difference. As I stated in an earlier post when I was putting on the ignition wires I accidently knocked the distributer cap off which in turn knocked out the center coil spring loaded contact that engages the rotor arm. After trying to start the car I discover this and was able to reassemble the distributer cap but it may not be a good enough connection.

I just spoke to Matt at MWB to see about a new distributor cap and we got taking about this issue. In the end he stated that it sounded like a timing issue. Which all looks good but who knows. I will try to test that before moving forward.
 
Hey.......just noticed something !!!!!

Might be an illusion or I am not seeing my small screen correctly......BUT...kinda looks like you have all the plugs wires out of order....

Looking at your video #1......and going by the #s you have written on your cap.....they look to be out of order....

Look at the pic below from Josh's engine. Look at the order of the wires coming off the cap.....sure looks different than yours...

Fiat X1/9 premium ignition wire sets

Add my name to the long list of fans of these wires. Just installed a set (in blue) on my '87, and they are every bit as good as advertised - fit and quality are top-notch.
xwebforums.com
 
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Seems like every so often I need to chime in on the FI hose replacement discussion. You don't need any special clamps or hose 'kits'. All you need is this hose: https://belmetric.com/m7-5x13-5-smooth-cohline-high-pressure-rh7-5hp-2192-0600/

Replacing the hoses is the easiest thing to do on these cars. Toughest part is getting the 35 year old rock hard hoses off, that can be a bitch sometimes. I wrote this up like 20 years ago: http://www.vayardo.com/SuperTopo/Tech/X19Tech/FI_Hose_Repair/FI_hoses.html

And I just did this on my son's '86:

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1690838397007.png


Yeah, that's all there is to it. No, you don't need clamps of any kind if you use the right hose. 7.5mm not 8. And readily available.
 

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I remember when this was on Lalo's Garage. It was a tremendous help the first time I replaced the FI hoses on my '79 X1/9.
 
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