63. It’s all fun and games until someone runs out of fuel

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The teething issues continue…

I recently started shooting a few segments to post on YouTube.  I have no starry-eyed dreams of becoming an “influencer” (I hate that term) but I thought it was about time to get some fresh SLC content onto the second most visited website on the World Wide Web.  What’s it saying about me when I remember the time before there was a WWW and social influencing?  Yikes!

If you haven’t watched my latest videos, check them out! – YouTube link

Anyway, I took the car out for a quick spin to shoot a few bits for an upcoming video when things went sideways from out of nowhere, check out the video here: Stranded! – YouTube link

I was lucky enough to have had the car die right in the middle of rush hour – lots of people angrily zipping around me for causing traffic but a few good Samaritans among them who helped me push the SLC off the main drag and onto a quieter side street.  Unfortunately I had a pretty good idea of what the issue might be.

In the seconds after the engine stalled and died I tried to hit the ignition – but the sound of silence was deafening for more than one reason.  The most obvious thing to me was the lack of noise from my high pressure fuel pump.  I’m running 2 external pumps, a Walbro low pressure lift pump which feeds my surge tank and a Bosch 044 high pressure pump.  The Bosch is super loud – like obnoxiously loud.  Its constant whirr can be heard even over the exhaust note.  Well, it wasn’t making any noise.

After getting the car pulled over I checked all the obvious things;

Fuses – check
Loose wire – check
Relays – check
Reset security system – check

Everything seemed to be OK except the pump wasn’t coming to life – sound familiar? Time-warp link

Being the second Bosch 044 pump to go out on me, I’m faced with the hard truth that there’s something about my fuel setup that’s killing my HP pumps.

Things that would cause this pump to fail:
– Running out of fuel
– Heat
– Electrical
– Clogged filters
– Vibration

If you’ve watched my “It’s Weird” video, recall one of the quirks of my fuel system is my fuel level gauge fails to read anything less than ~2 gallons.  At the time the car died I was showing about 6 gallons, so it’s unlikely my main tank was run dry.  When my father-in-law showed up with the trailer he also brought a few gallons of fuel, which we added to the tank.  The car did not respond any better to having more fuel.  NOPE.

This being an external pump, it’s also exposed to more heat than most typical fuel pumps since it gets hit by hot air circulating in the engine compartment.  I’ve mounted the pump in a fairly exposed area of the chassis and there’s a heat shield between it and the exhaust.  I’d only driven a few miles and the pump body was still relatively cool to the touch.  Plausible but unlikely.

Internal heat generation could be an issue; if the surge tank gets drained and there isn’t enough fuel flow going to the HP pump, it’ll cause the pump to cavitate and generate internal heat.  I wasn’t pulling any hard Gs and there weren’t any signs of intermittent fuel – just running awesome, then dead.  The low pressure pump I have is actually rated for high pressure/flow applications – so long as it’s getting fuel from the main tank it’s not likely this pump is cavitating/failing to fill the surge tank.  Plausible but unlikely.

As with the last time this pump failed, I did all the usual electrical checks.  My LP and HP pump are both fed off the same signal and power wire which split into separate lengths of ~13” wires before attaching to either pump.  I could hear the whirr of the LP pump but not the HP so the source power and signal are good.  Fuses for each individual line were also intact.  Electrical?  NOPE.

Filters clean – NOPE.

Vibration.  This one’s tough.  These pumps don’t come with acceptable vibration limits and I wouldn’t be able to accurately measure vibration anyway.  My LP pump is retained via rubber lined clamps but my HP pump is secured via a cool looking machined bracket that’s mounted to a thin aluminum plate.  The pump itself partly hangs off the frame rail but is supported from underneath by a piece of angle.  The combination of “meh” structural mounting and stiff bracketry combined may be adding up to high vibration levels making their way into the pump, causing the electronics to either shake apart or exceed their design limits.  I feel like it’s a bit of a stretch to put my pump failures on vibration but it’s one of the most likely of the causes I can think of.  Plausible.

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Here’s a photo of my fuel system setup.  The surge tank provided by Superlite was wrapped in Second Skin Thermal Block to try and keep the fuel cool.  My Walbro LP pump is hidden beneath the surge tank and the pesky Bosch 044 HP pump can be seen front and center.

Last potential cause?  I’ve been getting junk counterfeit pumps.  Check out this video if you’re really curious: YouTube link

For some reason the Bosch 044 fuel pumps have been declared verboten for sale in the State of California.  The only way I could source my 2 Bosch pumps was to go the way of eBay – and of course only the genuine legitimate stuff is sold on eBay, right?  The knock-off pumps are notorious for having very short lifespans and apparently the Bosch 044 is one of the most (if not the most) popular pump to counterfeit – hmm….

I have 2 possible solutions to my dilemma;
1 – Replace the pump, revise the mounting method and install some rubber isolators.  Of course I would have to find a way to circumvent the California issue so I could ensure I sourced my THIRD pump from a legitimate source.
2 – Throw money at it and really change things up.

Option 1 is the more wallet friendly solution and would help me diagnose the real cause of my failures.  Option 2 will cost more, but is the nuclear solution when maybe just a small change is needed.

I decided to go with Option 2.  I generally don’t like this approach but the difference in dollars is relatively low and Option 2 allows me to address multiple potential causes at the same time – I’m not confident in putting all my eggs into the vibration theory (assuming neither of my pumps were counterfeit).

Half the fun of this project (maybe more?) is having an excuse to buy new parts and tools!  So look what Mr Brown brought for me …

It’s an integrated surge tank/fuel pump unit made by FiTech.  This unit’s going to replace my HP pump and the surge tank provided with the kit.

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Box looks a bit dated but it’s what’s inside that counts, right?
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Aaaah … so pretty … super well packaged, it would take a lot of abuse for this assembly to arrive damaged.  +1 for the package designer who worked on this!
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The tank, a few electrical connectors and instructions, what more could you want?

Why’s this solution “better”?

Better heat management: the HP pump will now be residing INSIDE the surge tank. This means it’ll be bathed and surrounded by constantly circulating fuel, keeping internal temps low and isolating the pump from any exhaust heat.

Cavitation: there’s basically zero chance the HP pump will cavitate since it’s pickup will be at the base of the surge tank.  Assuming my LP pump can keep up (which I believe it can), the HP pump will never be starved of fuel.

Vibration: since the HP pump is surrounded by fuel, the fuel will act as a damper, helping to damp out any vibration coming in from the chassis.

No more Bosch 044 pump, so little to no chance the pump in this bad boy is a knock-off.

And most important, it looks a lot cooler!

Here’s a general video showing some of the products FiTech offers – note, I paid full retail for my surge tank and am not a paid spokesman (but if someone from FiTech reads this and is interested in sponsoring me please let me know!) – I just think their stuff is really cool.  YouTube link.

At this point you may be asking – “What’s a surge tank?”.  That’s a great question!  And my very short answer is it’s a small external fuel tank that’s used to ensure your engine is never starved of fuel under high-G driving conditions (such as those encountered in drag or road racing).  For a deeper explanation of why it’s a good idea to have a surge tank, follow this YouTube link.

OK, that’s probably enough rambling for today.  The next installment will go over the fuel system teardown and re-install.

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